mirror of https://github.com/grpc/grpc.git
Nicolas Noble
9 years ago
committed by
Nicolas "Pixel" Noble
commit
88966ab145
441 changed files with 12527 additions and 5104 deletions
File diff suppressed because it is too large
Load Diff
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Load Balancing in gRPC |
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======================= |
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# Objective |
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To design a load balancing API between a gRPC client and a Load Balancer to |
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instruct the client how to send load to multiple backend servers. |
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# Background |
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Prior to any gRPC specifics, we explore some usual ways to approach load |
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balancing. |
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### Proxy Model |
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Using a proxy provides a solid trustable client that can report load to the load |
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balancing system. Proxies typically require more resources to operate since they |
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have temporary copies of the RPC request and response. This model also increases |
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latency to the RPCs. |
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The proxy model was deemed inefficient when considering request heavy services |
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like storage. |
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### Balancing-aware Client |
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This thicker client places more of the load balancing logic in the client. For |
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example, the client could contain many load balancing policies (Round Robin, |
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Random, etc) used to select servers from a list. In this model, a list of |
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servers would be either statically configured in the client, provided by the |
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name resolution system, an external load balancer, etc. In any case, the client |
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is responsible for choosing the preferred server from the list. |
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One of the drawbacks of this approach is writing and maintaining the load |
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balancing policies in multiple languages and/or versions of the clients. These |
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policies can be fairly complicated. Some of the algorithms also require client |
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to server communication so the client would need to get thicker to support |
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additional RPCs to get health or load information in addition to sending RPCs |
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for user requests. |
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It would also significantly complicate the client's code: the new design hides |
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the load balancing complexity of multiple layers and presents it as a simple |
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list of servers to the client. |
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### External Load Balancing Service |
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The client load balancing code is kept simple and portable, implementing |
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well-known algorithms (ie, Round Robin) for server selection. |
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Complex load balancing algorithms are instead provided by the load balancer. The |
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client relies on the load balancer to provide _load balancing configuration_ and |
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_the list of servers_ to which the client should send requests. The balancer |
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updates the server list as needed to balance the load as well as handle server |
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unavailability or health issues. The load balancer will make any necessary |
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complex decisions and inform the client. The load balancer may communicate with |
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the backend servers to collect load and health information. |
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# Proposed Architecture |
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The gRPC load balancing approach follows the third approach, by having an |
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external load balancer which provides simple clients with a list of servers. |
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## Client |
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When establishing a gRPC stream to the balancer, the client will send an initial |
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request to the load balancer (via a regular gRPC message). The load balancer |
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will respond with client config (including, for example, settings for flow |
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control, RPC deadlines, etc.) or a redirect to another load balancer. If the |
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balancer did not redirect the client, it will then send a list of servers to the |
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client. The client will contain simple load balancing logic for choosing the |
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next server when it needs to send a request. |
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## Load Balancer |
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The Load Balancer is responsible for providing the client with a list of servers |
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and client RPC parameters. The balancer chooses when to update the list of |
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servers and can decide whether to provide a complete list, a subset, or a |
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specific list of “picked” servers in a particular order. The balancer can |
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optionally provide an expiration interval after which the server list should no |
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longer be trusted and should be updated by the balancer. |
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The load balancer may open reporting streams to each server contained in the |
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server list. These streams are primarily used for load reporting. For example, |
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Weighted Round Robin requires that the servers report utilization to the load |
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balancer in order to compute the next list of servers. |
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## Server |
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The gRPC Server is responsible for answering RPC requests and providing |
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responses to the client. The server will also report load to the load balancer |
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if a reporting stream was opened for this purpose. |
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### Security |
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The load balancer may be separate from the actual server backends and a |
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compromise of the load balancer should only lead to a compromise of the |
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loadbalancing functionality. In other words, a compromised load balancer should |
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not be able to cause a client to trust a (potentially malicious) backend server |
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any more than in a comparable situation without loadbalancing. |
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@ -0,0 +1,600 @@ |
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/*
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* |
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* Copyright 2015-2016, Google Inc. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions are |
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* met: |
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* |
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* * Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* * Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following disclaimer |
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* in the documentation and/or other materials provided with the |
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* distribution. |
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* * Neither the name of Google Inc. nor the names of its |
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* contributors may be used to endorse or promote products derived from |
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* this software without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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* |
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*/ |
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// Implements an efficient in-memory log, optimized for multiple writers and
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// a single reader. Available log space is divided up in blocks of
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// CENSUS_LOG_2_MAX_RECORD_SIZE bytes. A block can be in one of the following
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// three data structures:
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// - Free blocks (free_block_list)
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// - Blocks with unread data (dirty_block_list)
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// - Blocks currently attached to cores (core_local_blocks[])
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//
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// census_log_start_write() moves a block from core_local_blocks[] to the end of
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// dirty_block_list when block:
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// - is out-of-space OR
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// - has an incomplete record (an incomplete record occurs when a thread calls
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// census_log_start_write() and is context-switched before calling
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// census_log_end_write()
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// So, blocks in dirty_block_list are ordered, from oldest to newest, by the
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// time when block is detached from the core.
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//
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// census_log_read_next() first iterates over dirty_block_list and then
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// core_local_blocks[]. It moves completely read blocks from dirty_block_list
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// to free_block_list. Blocks in core_local_blocks[] are not freed, even when
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// completely read.
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//
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// If the log is configured to discard old records and free_block_list is empty,
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// census_log_start_write() iterates over dirty_block_list to allocate a
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// new block. It moves the oldest available block (no pending read/write) to
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// core_local_blocks[].
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//
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// core_local_block_struct is used to implement a map from core id to the block
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// associated with that core. This mapping is advisory. It is possible that the
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// block returned by this mapping is no longer associated with that core. This
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// mapping is updated, lazily, by census_log_start_write().
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//
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// Locking in block struct:
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//
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// Exclusive g_log.lock must be held before calling any functions operating on
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// block structs except census_log_start_write() and census_log_end_write().
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//
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// Writes to a block are serialized via writer_lock. census_log_start_write()
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// acquires this lock and census_log_end_write() releases it. On failure to
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// acquire the lock, writer allocates a new block for the current core and
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// updates core_local_block accordingly.
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//
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// Simultaneous read and write access is allowed. Readers can safely read up to
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// committed bytes (bytes_committed).
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//
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// reader_lock protects the block, currently being read, from getting recycled.
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// start_read() acquires reader_lock and end_read() releases the lock.
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//
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// Read/write access to a block is disabled via try_disable_access(). It returns
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// with both writer_lock and reader_lock held. These locks are subsequently
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// released by enable_access() to enable access to the block.
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//
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// A note on naming: Most function/struct names are prepended by cl_
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// (shorthand for census_log). Further, functions that manipulate structures
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// include the name of the structure, which will be passed as the first
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// argument. E.g. cl_block_initialize() will initialize a cl_block.
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#include "src/core/census/mlog.h" |
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#include <grpc/support/alloc.h> |
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#include <grpc/support/atm.h> |
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#include <grpc/support/cpu.h> |
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#include <grpc/support/log.h> |
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#include <grpc/support/sync.h> |
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#include <grpc/support/useful.h> |
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#include <stdbool.h> |
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#include <string.h> |
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// End of platform specific code
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typedef struct census_log_block_list_struct { |
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struct census_log_block_list_struct* next; |
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struct census_log_block_list_struct* prev; |
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struct census_log_block* block; |
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} cl_block_list_struct; |
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typedef struct census_log_block { |
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// Pointer to underlying buffer.
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char* buffer; |
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gpr_atm writer_lock; |
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gpr_atm reader_lock; |
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// Keeps completely written bytes. Declared atomic because accessed
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// simultaneously by reader and writer.
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gpr_atm bytes_committed; |
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// Bytes already read.
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size_t bytes_read; |
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// Links for list.
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cl_block_list_struct link; |
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// We want this structure to be cacheline aligned. We assume the following
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// sizes for the various parts on 32/64bit systems:
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// type 32b size 64b size
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// char* 4 8
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// 3x gpr_atm 12 24
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// size_t 4 8
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// cl_block_list_struct 12 24
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// TOTAL 32 64
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//
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// Depending on the size of our cacheline and the architecture, we
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// selectively add char buffering to this structure. The size is checked
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// via assert in census_log_initialize().
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#if defined(GPR_ARCH_64) |
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#define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 64) |
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#else |
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#if defined(GPR_ARCH_32) |
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#define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 32) |
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#else |
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#error "Unknown architecture" |
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#endif |
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#endif |
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#if CL_BLOCK_PAD_SIZE > 0 |
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char padding[CL_BLOCK_PAD_SIZE]; |
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#endif |
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} cl_block; |
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// A list of cl_blocks, doubly-linked through cl_block::link.
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typedef struct census_log_block_list { |
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int32_t count; // Number of items in list.
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cl_block_list_struct ht; // head/tail of linked list.
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} cl_block_list; |
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// Cacheline aligned block pointers to avoid false sharing. Block pointer must
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// be initialized via set_block(), before calling other functions
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typedef struct census_log_core_local_block { |
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gpr_atm block; |
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// Ensure cachline alignment: we assume sizeof(gpr_atm) == 4 or 8
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#if defined(GPR_ARCH_64) |
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#define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 8) |
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#else |
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#if defined(GPR_ARCH_32) |
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#define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 4) |
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#else |
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#error "Unknown architecture" |
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#endif |
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#endif |
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#if CL_CORE_LOCAL_BLOCK_PAD_SIZE > 0 |
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char padding[CL_CORE_LOCAL_BLOCK_PAD_SIZE]; |
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#endif |
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} cl_core_local_block; |
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struct census_log { |
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int discard_old_records; |
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// Number of cores (aka hardware-contexts)
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unsigned num_cores; |
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// number of CENSUS_LOG_2_MAX_RECORD_SIZE blocks in log
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uint32_t num_blocks; |
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cl_block* blocks; // Block metadata.
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cl_core_local_block* core_local_blocks; // Keeps core to block mappings.
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gpr_mu lock; |
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int initialized; // has log been initialized?
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// Keeps the state of the reader iterator. A value of 0 indicates that
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// iterator has reached the end. census_log_init_reader() resets the value
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// to num_core to restart iteration.
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uint32_t read_iterator_state; |
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// Points to the block being read. If non-NULL, the block is locked for
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// reading(block_being_read_->reader_lock is held).
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cl_block* block_being_read; |
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char* buffer; |
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cl_block_list free_block_list; |
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cl_block_list dirty_block_list; |
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gpr_atm out_of_space_count; |
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}; |
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// Single internal log.
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static struct census_log g_log; |
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// Functions that operate on an atomic memory location used as a lock.
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// Returns non-zero if lock is acquired.
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static int cl_try_lock(gpr_atm* lock) { return gpr_atm_acq_cas(lock, 0, 1); } |
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static void cl_unlock(gpr_atm* lock) { gpr_atm_rel_store(lock, 0); } |
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// Functions that operate on cl_core_local_block's.
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static void cl_core_local_block_set_block(cl_core_local_block* clb, |
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cl_block* block) { |
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gpr_atm_rel_store(&clb->block, (gpr_atm)block); |
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} |
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static cl_block* cl_core_local_block_get_block(cl_core_local_block* clb) { |
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return (cl_block*)gpr_atm_acq_load(&clb->block); |
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} |
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// Functions that operate on cl_block_list_struct's.
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static void cl_block_list_struct_initialize(cl_block_list_struct* bls, |
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cl_block* block) { |
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bls->next = bls->prev = bls; |
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bls->block = block; |
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} |
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// Functions that operate on cl_block_list's.
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static void cl_block_list_initialize(cl_block_list* list) { |
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list->count = 0; |
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cl_block_list_struct_initialize(&list->ht, NULL); |
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} |
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// Returns head of *this, or NULL if empty.
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static cl_block* cl_block_list_head(cl_block_list* list) { |
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return list->ht.next->block; |
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} |
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// Insert element *e after *pos.
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static void cl_block_list_insert(cl_block_list* list, cl_block_list_struct* pos, |
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cl_block_list_struct* e) { |
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list->count++; |
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e->next = pos->next; |
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e->prev = pos; |
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e->next->prev = e; |
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e->prev->next = e; |
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} |
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// Insert block at the head of the list
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static void cl_block_list_insert_at_head(cl_block_list* list, cl_block* block) { |
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cl_block_list_insert(list, &list->ht, &block->link); |
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} |
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// Insert block at the tail of the list.
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static void cl_block_list_insert_at_tail(cl_block_list* list, cl_block* block) { |
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cl_block_list_insert(list, list->ht.prev, &block->link); |
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} |
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// Removes block *b. Requires *b be in the list.
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static void cl_block_list_remove(cl_block_list* list, cl_block* b) { |
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list->count--; |
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b->link.next->prev = b->link.prev; |
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b->link.prev->next = b->link.next; |
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} |
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// Functions that operate on cl_block's
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static void cl_block_initialize(cl_block* block, char* buffer) { |
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block->buffer = buffer; |
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gpr_atm_rel_store(&block->writer_lock, 0); |
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gpr_atm_rel_store(&block->reader_lock, 0); |
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gpr_atm_rel_store(&block->bytes_committed, 0); |
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block->bytes_read = 0; |
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cl_block_list_struct_initialize(&block->link, block); |
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} |
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// Guards against exposing partially written buffer to the reader.
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static void cl_block_set_bytes_committed(cl_block* block, |
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size_t bytes_committed) { |
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gpr_atm_rel_store(&block->bytes_committed, (gpr_atm)bytes_committed); |
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} |
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|
||||||
|
static size_t cl_block_get_bytes_committed(cl_block* block) { |
||||||
|
return (size_t)gpr_atm_acq_load(&block->bytes_committed); |
||||||
|
} |
||||||
|
|
||||||
|
// Tries to disable future read/write access to this block. Succeeds if:
|
||||||
|
// - no in-progress write AND
|
||||||
|
// - no in-progress read AND
|
||||||
|
// - 'discard_data' set to true OR no unread data
|
||||||
|
// On success, clears the block state and returns with writer_lock_ and
|
||||||
|
// reader_lock_ held. These locks are released by a subsequent
|
||||||
|
// cl_block_access_enable() call.
|
||||||
|
static bool cl_block_try_disable_access(cl_block* block, int discard_data) { |
||||||
|
if (!cl_try_lock(&block->writer_lock)) { |
||||||
|
return false; |
||||||
|
} |
||||||
|
if (!cl_try_lock(&block->reader_lock)) { |
||||||
|
cl_unlock(&block->writer_lock); |
||||||
|
return false; |
||||||
|
} |
||||||
|
if (!discard_data && |
||||||
|
(block->bytes_read != cl_block_get_bytes_committed(block))) { |
||||||
|
cl_unlock(&block->reader_lock); |
||||||
|
cl_unlock(&block->writer_lock); |
||||||
|
return false; |
||||||
|
} |
||||||
|
cl_block_set_bytes_committed(block, 0); |
||||||
|
block->bytes_read = 0; |
||||||
|
return true; |
||||||
|
} |
||||||
|
|
||||||
|
static void cl_block_enable_access(cl_block* block) { |
||||||
|
cl_unlock(&block->reader_lock); |
||||||
|
cl_unlock(&block->writer_lock); |
||||||
|
} |
||||||
|
|
||||||
|
// Returns with writer_lock held.
|
||||||
|
static void* cl_block_start_write(cl_block* block, size_t size) { |
||||||
|
if (!cl_try_lock(&block->writer_lock)) { |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
size_t bytes_committed = cl_block_get_bytes_committed(block); |
||||||
|
if (bytes_committed + size > CENSUS_LOG_MAX_RECORD_SIZE) { |
||||||
|
cl_unlock(&block->writer_lock); |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
return block->buffer + bytes_committed; |
||||||
|
} |
||||||
|
|
||||||
|
// Releases writer_lock and increments committed bytes by 'bytes_written'.
|
||||||
|
// 'bytes_written' must be <= 'size' specified in the corresponding
|
||||||
|
// StartWrite() call. This function is thread-safe.
|
||||||
|
static void cl_block_end_write(cl_block* block, size_t bytes_written) { |
||||||
|
cl_block_set_bytes_committed( |
||||||
|
block, cl_block_get_bytes_committed(block) + bytes_written); |
||||||
|
cl_unlock(&block->writer_lock); |
||||||
|
} |
||||||
|
|
||||||
|
// Returns a pointer to the first unread byte in buffer. The number of bytes
|
||||||
|
// available are returned in 'bytes_available'. Acquires reader lock that is
|
||||||
|
// released by a subsequent cl_block_end_read() call. Returns NULL if:
|
||||||
|
// - read in progress
|
||||||
|
// - no data available
|
||||||
|
static void* cl_block_start_read(cl_block* block, size_t* bytes_available) { |
||||||
|
if (!cl_try_lock(&block->reader_lock)) { |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
// bytes_committed may change from under us. Use bytes_available to update
|
||||||
|
// bytes_read below.
|
||||||
|
size_t bytes_committed = cl_block_get_bytes_committed(block); |
||||||
|
GPR_ASSERT(bytes_committed >= block->bytes_read); |
||||||
|
*bytes_available = bytes_committed - block->bytes_read; |
||||||
|
if (*bytes_available == 0) { |
||||||
|
cl_unlock(&block->reader_lock); |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
void* record = block->buffer + block->bytes_read; |
||||||
|
block->bytes_read += *bytes_available; |
||||||
|
return record; |
||||||
|
} |
||||||
|
|
||||||
|
static void cl_block_end_read(cl_block* block) { |
||||||
|
cl_unlock(&block->reader_lock); |
||||||
|
} |
||||||
|
|
||||||
|
// Internal functions operating on g_log
|
||||||
|
|
||||||
|
// Allocates a new free block (or recycles an available dirty block if log is
|
||||||
|
// configured to discard old records). Returns NULL if out-of-space.
|
||||||
|
static cl_block* cl_allocate_block(void) { |
||||||
|
cl_block* block = cl_block_list_head(&g_log.free_block_list); |
||||||
|
if (block != NULL) { |
||||||
|
cl_block_list_remove(&g_log.free_block_list, block); |
||||||
|
return block; |
||||||
|
} |
||||||
|
if (!g_log.discard_old_records) { |
||||||
|
// No free block and log is configured to keep old records.
|
||||||
|
return NULL; |
||||||
|
} |
||||||
|
// Recycle dirty block. Start from the oldest.
|
||||||
|
for (block = cl_block_list_head(&g_log.dirty_block_list); block != NULL; |
||||||
|
block = block->link.next->block) { |
||||||
|
if (cl_block_try_disable_access(block, 1 /* discard data */)) { |
||||||
|
cl_block_list_remove(&g_log.dirty_block_list, block); |
||||||
|
return block; |
||||||
|
} |
||||||
|
} |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
|
||||||
|
// Allocates a new block and updates core id => block mapping. 'old_block'
|
||||||
|
// points to the block that the caller thinks is attached to
|
||||||
|
// 'core_id'. 'old_block' may be NULL. Returns true if:
|
||||||
|
// - allocated a new block OR
|
||||||
|
// - 'core_id' => 'old_block' mapping changed (another thread allocated a
|
||||||
|
// block before lock was acquired).
|
||||||
|
static bool cl_allocate_core_local_block(uint32_t core_id, |
||||||
|
cl_block* old_block) { |
||||||
|
// Now that we have the lock, check if core-local mapping has changed.
|
||||||
|
cl_core_local_block* core_local_block = &g_log.core_local_blocks[core_id]; |
||||||
|
cl_block* block = cl_core_local_block_get_block(core_local_block); |
||||||
|
if ((block != NULL) && (block != old_block)) { |
||||||
|
return true; |
||||||
|
} |
||||||
|
if (block != NULL) { |
||||||
|
cl_core_local_block_set_block(core_local_block, NULL); |
||||||
|
cl_block_list_insert_at_tail(&g_log.dirty_block_list, block); |
||||||
|
} |
||||||
|
block = cl_allocate_block(); |
||||||
|
if (block == NULL) { |
||||||
|
return false; |
||||||
|
} |
||||||
|
cl_core_local_block_set_block(core_local_block, block); |
||||||
|
cl_block_enable_access(block); |
||||||
|
return true; |
||||||
|
} |
||||||
|
|
||||||
|
static cl_block* cl_get_block(void* record) { |
||||||
|
uintptr_t p = (uintptr_t)((char*)record - g_log.buffer); |
||||||
|
uintptr_t index = p >> CENSUS_LOG_2_MAX_RECORD_SIZE; |
||||||
|
return &g_log.blocks[index]; |
||||||
|
} |
||||||
|
|
||||||
|
// Gets the next block to read and tries to free 'prev' block (if not NULL).
|
||||||
|
// Returns NULL if reached the end.
|
||||||
|
static cl_block* cl_next_block_to_read(cl_block* prev) { |
||||||
|
cl_block* block = NULL; |
||||||
|
if (g_log.read_iterator_state == g_log.num_cores) { |
||||||
|
// We are traversing dirty list; find the next dirty block.
|
||||||
|
if (prev != NULL) { |
||||||
|
// Try to free the previous block if there is no unread data. This
|
||||||
|
// block
|
||||||
|
// may have unread data if previously incomplete record completed
|
||||||
|
// between
|
||||||
|
// read_next() calls.
|
||||||
|
block = prev->link.next->block; |
||||||
|
if (cl_block_try_disable_access(prev, 0 /* do not discard data */)) { |
||||||
|
cl_block_list_remove(&g_log.dirty_block_list, prev); |
||||||
|
cl_block_list_insert_at_head(&g_log.free_block_list, prev); |
||||||
|
} |
||||||
|
} else { |
||||||
|
block = cl_block_list_head(&g_log.dirty_block_list); |
||||||
|
} |
||||||
|
if (block != NULL) { |
||||||
|
return block; |
||||||
|
} |
||||||
|
// We are done with the dirty list; moving on to core-local blocks.
|
||||||
|
} |
||||||
|
while (g_log.read_iterator_state > 0) { |
||||||
|
g_log.read_iterator_state--; |
||||||
|
block = cl_core_local_block_get_block( |
||||||
|
&g_log.core_local_blocks[g_log.read_iterator_state]); |
||||||
|
if (block != NULL) { |
||||||
|
return block; |
||||||
|
} |
||||||
|
} |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
|
||||||
|
#define CL_LOG_2_MB 20 // 2^20 = 1MB
|
||||||
|
|
||||||
|
// External functions: primary stats_log interface
|
||||||
|
void census_log_initialize(size_t size_in_mb, int discard_old_records) { |
||||||
|
// Check cacheline alignment.
|
||||||
|
GPR_ASSERT(sizeof(cl_block) % GPR_CACHELINE_SIZE == 0); |
||||||
|
GPR_ASSERT(sizeof(cl_core_local_block) % GPR_CACHELINE_SIZE == 0); |
||||||
|
GPR_ASSERT(!g_log.initialized); |
||||||
|
g_log.discard_old_records = discard_old_records; |
||||||
|
g_log.num_cores = gpr_cpu_num_cores(); |
||||||
|
// Ensure that we will not get any overflow in calaculating num_blocks
|
||||||
|
GPR_ASSERT(CL_LOG_2_MB >= CENSUS_LOG_2_MAX_RECORD_SIZE); |
||||||
|
GPR_ASSERT(size_in_mb < 1000); |
||||||
|
// Ensure at least 2x as many blocks as there are cores.
|
||||||
|
g_log.num_blocks = |
||||||
|
(uint32_t)GPR_MAX(2 * g_log.num_cores, (size_in_mb << CL_LOG_2_MB) >> |
||||||
|
CENSUS_LOG_2_MAX_RECORD_SIZE); |
||||||
|
gpr_mu_init(&g_log.lock); |
||||||
|
g_log.read_iterator_state = 0; |
||||||
|
g_log.block_being_read = NULL; |
||||||
|
g_log.core_local_blocks = (cl_core_local_block*)gpr_malloc_aligned( |
||||||
|
g_log.num_cores * sizeof(cl_core_local_block), GPR_CACHELINE_SIZE_LOG); |
||||||
|
memset(g_log.core_local_blocks, 0, |
||||||
|
g_log.num_cores * sizeof(cl_core_local_block)); |
||||||
|
g_log.blocks = (cl_block*)gpr_malloc_aligned( |
||||||
|
g_log.num_blocks * sizeof(cl_block), GPR_CACHELINE_SIZE_LOG); |
||||||
|
memset(g_log.blocks, 0, g_log.num_blocks * sizeof(cl_block)); |
||||||
|
g_log.buffer = gpr_malloc(g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE); |
||||||
|
memset(g_log.buffer, 0, g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE); |
||||||
|
cl_block_list_initialize(&g_log.free_block_list); |
||||||
|
cl_block_list_initialize(&g_log.dirty_block_list); |
||||||
|
for (uint32_t i = 0; i < g_log.num_blocks; ++i) { |
||||||
|
cl_block* block = g_log.blocks + i; |
||||||
|
cl_block_initialize(block, g_log.buffer + (CENSUS_LOG_MAX_RECORD_SIZE * i)); |
||||||
|
cl_block_try_disable_access(block, 1 /* discard data */); |
||||||
|
cl_block_list_insert_at_tail(&g_log.free_block_list, block); |
||||||
|
} |
||||||
|
gpr_atm_rel_store(&g_log.out_of_space_count, 0); |
||||||
|
g_log.initialized = 1; |
||||||
|
} |
||||||
|
|
||||||
|
void census_log_shutdown(void) { |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
gpr_mu_destroy(&g_log.lock); |
||||||
|
gpr_free_aligned(g_log.core_local_blocks); |
||||||
|
g_log.core_local_blocks = NULL; |
||||||
|
gpr_free_aligned(g_log.blocks); |
||||||
|
g_log.blocks = NULL; |
||||||
|
gpr_free(g_log.buffer); |
||||||
|
g_log.buffer = NULL; |
||||||
|
g_log.initialized = 0; |
||||||
|
} |
||||||
|
|
||||||
|
void* census_log_start_write(size_t size) { |
||||||
|
// Used to bound number of times block allocation is attempted.
|
||||||
|
GPR_ASSERT(size > 0); |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
if (size > CENSUS_LOG_MAX_RECORD_SIZE) { |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
uint32_t attempts_remaining = g_log.num_blocks; |
||||||
|
uint32_t core_id = gpr_cpu_current_cpu(); |
||||||
|
do { |
||||||
|
void* record = NULL; |
||||||
|
cl_block* block = |
||||||
|
cl_core_local_block_get_block(&g_log.core_local_blocks[core_id]); |
||||||
|
if (block && (record = cl_block_start_write(block, size))) { |
||||||
|
return record; |
||||||
|
} |
||||||
|
// Need to allocate a new block. We are here if:
|
||||||
|
// - No block associated with the core OR
|
||||||
|
// - Write in-progress on the block OR
|
||||||
|
// - block is out of space
|
||||||
|
gpr_mu_lock(&g_log.lock); |
||||||
|
bool allocated = cl_allocate_core_local_block(core_id, block); |
||||||
|
gpr_mu_unlock(&g_log.lock); |
||||||
|
if (!allocated) { |
||||||
|
gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1); |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
} while (attempts_remaining--); |
||||||
|
// Give up.
|
||||||
|
gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1); |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
|
||||||
|
void census_log_end_write(void* record, size_t bytes_written) { |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
cl_block_end_write(cl_get_block(record), bytes_written); |
||||||
|
} |
||||||
|
|
||||||
|
void census_log_init_reader(void) { |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
gpr_mu_lock(&g_log.lock); |
||||||
|
// If a block is locked for reading unlock it.
|
||||||
|
if (g_log.block_being_read != NULL) { |
||||||
|
cl_block_end_read(g_log.block_being_read); |
||||||
|
g_log.block_being_read = NULL; |
||||||
|
} |
||||||
|
g_log.read_iterator_state = g_log.num_cores; |
||||||
|
gpr_mu_unlock(&g_log.lock); |
||||||
|
} |
||||||
|
|
||||||
|
const void* census_log_read_next(size_t* bytes_available) { |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
gpr_mu_lock(&g_log.lock); |
||||||
|
if (g_log.block_being_read != NULL) { |
||||||
|
cl_block_end_read(g_log.block_being_read); |
||||||
|
} |
||||||
|
do { |
||||||
|
g_log.block_being_read = cl_next_block_to_read(g_log.block_being_read); |
||||||
|
if (g_log.block_being_read != NULL) { |
||||||
|
void* record = |
||||||
|
cl_block_start_read(g_log.block_being_read, bytes_available); |
||||||
|
if (record != NULL) { |
||||||
|
gpr_mu_unlock(&g_log.lock); |
||||||
|
return record; |
||||||
|
} |
||||||
|
} |
||||||
|
} while (g_log.block_being_read != NULL); |
||||||
|
gpr_mu_unlock(&g_log.lock); |
||||||
|
return NULL; |
||||||
|
} |
||||||
|
|
||||||
|
size_t census_log_remaining_space(void) { |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
size_t space = 0; |
||||||
|
gpr_mu_lock(&g_log.lock); |
||||||
|
if (g_log.discard_old_records) { |
||||||
|
// Remaining space is not meaningful; just return the entire log space.
|
||||||
|
space = g_log.num_blocks << CENSUS_LOG_2_MAX_RECORD_SIZE; |
||||||
|
} else { |
||||||
|
GPR_ASSERT(g_log.free_block_list.count >= 0); |
||||||
|
space = (size_t)g_log.free_block_list.count * CENSUS_LOG_MAX_RECORD_SIZE; |
||||||
|
} |
||||||
|
gpr_mu_unlock(&g_log.lock); |
||||||
|
return space; |
||||||
|
} |
||||||
|
|
||||||
|
int64_t census_log_out_of_space_count(void) { |
||||||
|
GPR_ASSERT(g_log.initialized); |
||||||
|
return gpr_atm_acq_load(&g_log.out_of_space_count); |
||||||
|
} |
||||||
@ -0,0 +1,95 @@ |
|||||||
|
/*
|
||||||
|
* |
||||||
|
* Copyright 2015-2016, Google Inc. |
||||||
|
* All rights reserved. |
||||||
|
* |
||||||
|
* Redistribution and use in source and binary forms, with or without |
||||||
|
* modification, are permitted provided that the following conditions are |
||||||
|
* met: |
||||||
|
* |
||||||
|
* * Redistributions of source code must retain the above copyright |
||||||
|
* notice, this list of conditions and the following disclaimer. |
||||||
|
* * Redistributions in binary form must reproduce the above |
||||||
|
* copyright notice, this list of conditions and the following disclaimer |
||||||
|
* in the documentation and/or other materials provided with the |
||||||
|
* distribution. |
||||||
|
* * Neither the name of Google Inc. nor the names of its |
||||||
|
* contributors may be used to endorse or promote products derived from |
||||||
|
* this software without specific prior written permission. |
||||||
|
* |
||||||
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
||||||
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
||||||
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
||||||
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
||||||
|
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
||||||
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
||||||
|
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
||||||
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
||||||
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
||||||
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
||||||
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||||||
|
* |
||||||
|
*/ |
||||||
|
|
||||||
|
/* A very fast in-memory log, optimized for multiple writers. */ |
||||||
|
|
||||||
|
#ifndef GRPC_INTERNAL_CORE_CENSUS_MLOG_H |
||||||
|
#define GRPC_INTERNAL_CORE_CENSUS_MLOG_H |
||||||
|
|
||||||
|
#include <grpc/support/port_platform.h> |
||||||
|
#include <stddef.h> |
||||||
|
|
||||||
|
/* Maximum record size, in bytes. */ |
||||||
|
#define CENSUS_LOG_2_MAX_RECORD_SIZE 14 /* 2^14 = 16KB */ |
||||||
|
#define CENSUS_LOG_MAX_RECORD_SIZE (1 << CENSUS_LOG_2_MAX_RECORD_SIZE) |
||||||
|
|
||||||
|
/* Initialize the statistics logging subsystem with the given log size. A log
|
||||||
|
size of 0 will result in the smallest possible log for the platform |
||||||
|
(approximately CENSUS_LOG_MAX_RECORD_SIZE * gpr_cpu_num_cores()). If |
||||||
|
discard_old_records is non-zero, then new records will displace older ones |
||||||
|
when the log is full. This function must be called before any other |
||||||
|
census_log functions. |
||||||
|
*/ |
||||||
|
void census_log_initialize(size_t size_in_mb, int discard_old_records); |
||||||
|
|
||||||
|
/* Shutdown the logging subsystem. Caller must ensure that:
|
||||||
|
- no in progress or future call to any census_log functions |
||||||
|
- no incomplete records |
||||||
|
*/ |
||||||
|
void census_log_shutdown(void); |
||||||
|
|
||||||
|
/* Allocates and returns a 'size' bytes record and marks it in use. A
|
||||||
|
subsequent census_log_end_write() marks the record complete. The |
||||||
|
'bytes_written' census_log_end_write() argument must be <= |
||||||
|
'size'. Returns NULL if out-of-space AND: |
||||||
|
- log is configured to keep old records OR |
||||||
|
- all blocks are pinned by incomplete records. |
||||||
|
*/ |
||||||
|
void* census_log_start_write(size_t size); |
||||||
|
|
||||||
|
void census_log_end_write(void* record, size_t bytes_written); |
||||||
|
|
||||||
|
void census_log_init_reader(void); |
||||||
|
|
||||||
|
/* census_log_read_next() iterates over blocks with data and for each block
|
||||||
|
returns a pointer to the first unread byte. The number of bytes that can be |
||||||
|
read are returned in 'bytes_available'. Reader is expected to read all |
||||||
|
available data. Reading the data consumes it i.e. it cannot be read again. |
||||||
|
census_log_read_next() returns NULL if the end is reached i.e last block |
||||||
|
is read. census_log_init_reader() starts the iteration or aborts the |
||||||
|
current iteration. |
||||||
|
*/ |
||||||
|
const void* census_log_read_next(size_t* bytes_available); |
||||||
|
|
||||||
|
/* Returns estimated remaining space across all blocks, in bytes. If log is
|
||||||
|
configured to discard old records, returns total log space. Otherwise, |
||||||
|
returns space available in empty blocks (partially filled blocks are |
||||||
|
treated as full). |
||||||
|
*/ |
||||||
|
size_t census_log_remaining_space(void); |
||||||
|
|
||||||
|
/* Returns the number of times gprc_stats_log_start_write() failed due to
|
||||||
|
out-of-space. */ |
||||||
|
int64_t census_log_out_of_space_count(void); |
||||||
|
|
||||||
|
#endif /* GRPC_INTERNAL_CORE_CENSUS_LOG_H */ |
||||||
@ -0,0 +1,259 @@ |
|||||||
|
//
|
||||||
|
//
|
||||||
|
// Copyright 2016, Google Inc.
|
||||||
|
// All rights reserved.
|
||||||
|
//
|
||||||
|
// Redistribution and use in source and binary forms, with or without
|
||||||
|
// modification, are permitted provided that the following conditions are
|
||||||
|
// met:
|
||||||
|
//
|
||||||
|
// * Redistributions of source code must retain the above copyright
|
||||||
|
// notice, this list of conditions and the following disclaimer.
|
||||||
|
// * Redistributions in binary form must reproduce the above
|
||||||
|
// copyright notice, this list of conditions and the following disclaimer
|
||||||
|
// in the documentation and/or other materials provided with the
|
||||||
|
// distribution.
|
||||||
|
// * Neither the name of Google Inc. nor the names of its
|
||||||
|
// contributors may be used to endorse or promote products derived from
|
||||||
|
// this software without specific prior written permission.
|
||||||
|
//
|
||||||
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||||||
|
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||||||
|
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
||||||
|
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
||||||
|
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
||||||
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
||||||
|
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||||
|
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
||||||
|
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||||||
|
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||||
|
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||||||
|
//
|
||||||
|
//
|
||||||
|
|
||||||
|
#include "src/core/client_config/subchannel_index.h" |
||||||
|
|
||||||
|
#include <stdbool.h> |
||||||
|
#include <string.h> |
||||||
|
|
||||||
|
#include <grpc/support/alloc.h> |
||||||
|
#include <grpc/support/avl.h> |
||||||
|
#include <grpc/support/tls.h> |
||||||
|
|
||||||
|
#include "src/core/channel/channel_args.h" |
||||||
|
|
||||||
|
// a map of subchannel_key --> subchannel, used for detecting connections
|
||||||
|
// to the same destination in order to share them
|
||||||
|
static gpr_avl g_subchannel_index; |
||||||
|
|
||||||
|
static gpr_mu g_mu; |
||||||
|
|
||||||
|
struct grpc_subchannel_key { |
||||||
|
grpc_connector *connector; |
||||||
|
grpc_subchannel_args args; |
||||||
|
}; |
||||||
|
|
||||||
|
GPR_TLS_DECL(subchannel_index_exec_ctx); |
||||||
|
|
||||||
|
static void enter_ctx(grpc_exec_ctx *exec_ctx) { |
||||||
|
GPR_ASSERT(gpr_tls_get(&subchannel_index_exec_ctx) == 0); |
||||||
|
gpr_tls_set(&subchannel_index_exec_ctx, (intptr_t)exec_ctx); |
||||||
|
} |
||||||
|
|
||||||
|
static void leave_ctx(grpc_exec_ctx *exec_ctx) { |
||||||
|
GPR_ASSERT(gpr_tls_get(&subchannel_index_exec_ctx) == (intptr_t)exec_ctx); |
||||||
|
gpr_tls_set(&subchannel_index_exec_ctx, 0); |
||||||
|
} |
||||||
|
|
||||||
|
static grpc_exec_ctx *current_ctx() { |
||||||
|
grpc_exec_ctx *c = (grpc_exec_ctx *)gpr_tls_get(&subchannel_index_exec_ctx); |
||||||
|
GPR_ASSERT(c != NULL); |
||||||
|
return c; |
||||||
|
} |
||||||
|
|
||||||
|
static grpc_subchannel_key *create_key( |
||||||
|
grpc_connector *connector, grpc_subchannel_args *args, |
||||||
|
grpc_channel_args *(*copy_channel_args)(const grpc_channel_args *args)) { |
||||||
|
grpc_subchannel_key *k = gpr_malloc(sizeof(*k)); |
||||||
|
k->connector = grpc_connector_ref(connector); |
||||||
|
k->args.filter_count = args->filter_count; |
||||||
|
k->args.filters = gpr_malloc(sizeof(*k->args.filters) * k->args.filter_count); |
||||||
|
memcpy((grpc_channel_filter *)k->args.filters, args->filters, |
||||||
|
sizeof(*k->args.filters) * k->args.filter_count); |
||||||
|
k->args.addr_len = args->addr_len; |
||||||
|
k->args.addr = gpr_malloc(args->addr_len); |
||||||
|
memcpy(k->args.addr, args->addr, k->args.addr_len); |
||||||
|
k->args.args = copy_channel_args(args->args); |
||||||
|
return k; |
||||||
|
} |
||||||
|
|
||||||
|
grpc_subchannel_key *grpc_subchannel_key_create(grpc_connector *connector, |
||||||
|
grpc_subchannel_args *args) { |
||||||
|
return create_key(connector, args, grpc_channel_args_normalize); |
||||||
|
} |
||||||
|
|
||||||
|
static grpc_subchannel_key *subchannel_key_copy(grpc_subchannel_key *k) { |
||||||
|
return create_key(k->connector, &k->args, grpc_channel_args_copy); |
||||||
|
} |
||||||
|
|
||||||
|
static int subchannel_key_compare(grpc_subchannel_key *a, |
||||||
|
grpc_subchannel_key *b) { |
||||||
|
int c = GPR_ICMP(a->connector, b->connector); |
||||||
|
if (c != 0) return c; |
||||||
|
c = GPR_ICMP(a->args.addr_len, b->args.addr_len); |
||||||
|
if (c != 0) return c; |
||||||
|
c = GPR_ICMP(a->args.filter_count, b->args.filter_count); |
||||||
|
if (c != 0) return c; |
||||||
|
c = memcmp(a->args.addr, b->args.addr, a->args.addr_len); |
||||||
|
if (c != 0) return c; |
||||||
|
c = memcmp(a->args.filters, b->args.filters, |
||||||
|
a->args.filter_count * sizeof(*a->args.filters)); |
||||||
|
return grpc_channel_args_compare(a->args.args, b->args.args); |
||||||
|
} |
||||||
|
|
||||||
|
void grpc_subchannel_key_destroy(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *k) { |
||||||
|
grpc_connector_unref(exec_ctx, k->connector); |
||||||
|
gpr_free(k->args.addr); |
||||||
|
gpr_free((grpc_channel_args *)k->args.filters); |
||||||
|
grpc_channel_args_destroy((grpc_channel_args *)k->args.args); |
||||||
|
gpr_free(k); |
||||||
|
} |
||||||
|
|
||||||
|
static void sck_avl_destroy(void *p) { |
||||||
|
grpc_subchannel_key_destroy(current_ctx(), p); |
||||||
|
} |
||||||
|
|
||||||
|
static void *sck_avl_copy(void *p) { return subchannel_key_copy(p); } |
||||||
|
|
||||||
|
static long sck_avl_compare(void *a, void *b) { |
||||||
|
return subchannel_key_compare(a, b); |
||||||
|
} |
||||||
|
|
||||||
|
static void scv_avl_destroy(void *p) { |
||||||
|
GRPC_SUBCHANNEL_WEAK_UNREF(current_ctx(), p, "subchannel_index"); |
||||||
|
} |
||||||
|
|
||||||
|
static void *scv_avl_copy(void *p) { |
||||||
|
GRPC_SUBCHANNEL_WEAK_REF(p, "subchannel_index"); |
||||||
|
return p; |
||||||
|
} |
||||||
|
|
||||||
|
static const gpr_avl_vtable subchannel_avl_vtable = { |
||||||
|
.destroy_key = sck_avl_destroy, |
||||||
|
.copy_key = sck_avl_copy, |
||||||
|
.compare_keys = sck_avl_compare, |
||||||
|
.destroy_value = scv_avl_destroy, |
||||||
|
.copy_value = scv_avl_copy}; |
||||||
|
|
||||||
|
void grpc_subchannel_index_init(void) { |
||||||
|
g_subchannel_index = gpr_avl_create(&subchannel_avl_vtable); |
||||||
|
gpr_mu_init(&g_mu); |
||||||
|
} |
||||||
|
|
||||||
|
void grpc_subchannel_index_shutdown(void) { |
||||||
|
gpr_mu_destroy(&g_mu); |
||||||
|
gpr_avl_unref(g_subchannel_index); |
||||||
|
} |
||||||
|
|
||||||
|
grpc_subchannel *grpc_subchannel_index_find(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key) { |
||||||
|
enter_ctx(exec_ctx); |
||||||
|
|
||||||
|
// Lock, and take a reference to the subchannel index.
|
||||||
|
// We don't need to do the search under a lock as avl's are immutable.
|
||||||
|
gpr_mu_lock(&g_mu); |
||||||
|
gpr_avl index = gpr_avl_ref(g_subchannel_index); |
||||||
|
gpr_mu_unlock(&g_mu); |
||||||
|
|
||||||
|
grpc_subchannel *c = |
||||||
|
GRPC_SUBCHANNEL_REF_FROM_WEAK_REF(gpr_avl_get(index, key), "index_find"); |
||||||
|
gpr_avl_unref(index); |
||||||
|
|
||||||
|
leave_ctx(exec_ctx); |
||||||
|
return c; |
||||||
|
} |
||||||
|
|
||||||
|
grpc_subchannel *grpc_subchannel_index_register(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key, |
||||||
|
grpc_subchannel *constructed) { |
||||||
|
enter_ctx(exec_ctx); |
||||||
|
|
||||||
|
grpc_subchannel *c = NULL; |
||||||
|
|
||||||
|
while (c == NULL) { |
||||||
|
// Compare and swap loop:
|
||||||
|
// - take a reference to the current index
|
||||||
|
gpr_mu_lock(&g_mu); |
||||||
|
gpr_avl index = gpr_avl_ref(g_subchannel_index); |
||||||
|
gpr_mu_unlock(&g_mu); |
||||||
|
|
||||||
|
// - Check to see if a subchannel already exists
|
||||||
|
c = gpr_avl_get(index, key); |
||||||
|
if (c != NULL) { |
||||||
|
// yes -> we're done
|
||||||
|
GRPC_SUBCHANNEL_WEAK_UNREF(exec_ctx, constructed, "index_register"); |
||||||
|
} else { |
||||||
|
// no -> update the avl and compare/swap
|
||||||
|
gpr_avl updated = |
||||||
|
gpr_avl_add(gpr_avl_ref(index), subchannel_key_copy(key), |
||||||
|
GRPC_SUBCHANNEL_WEAK_REF(constructed, "index_register")); |
||||||
|
|
||||||
|
// it may happen (but it's expected to be unlikely)
|
||||||
|
// that some other thread has changed the index:
|
||||||
|
// compare/swap here to check that, and retry as necessary
|
||||||
|
gpr_mu_lock(&g_mu); |
||||||
|
if (index.root == g_subchannel_index.root) { |
||||||
|
GPR_SWAP(gpr_avl, updated, g_subchannel_index); |
||||||
|
c = constructed; |
||||||
|
} |
||||||
|
gpr_mu_unlock(&g_mu); |
||||||
|
|
||||||
|
gpr_avl_unref(updated); |
||||||
|
} |
||||||
|
gpr_avl_unref(index); |
||||||
|
} |
||||||
|
|
||||||
|
leave_ctx(exec_ctx); |
||||||
|
|
||||||
|
return c; |
||||||
|
} |
||||||
|
|
||||||
|
void grpc_subchannel_index_unregister(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key, |
||||||
|
grpc_subchannel *constructed) { |
||||||
|
enter_ctx(exec_ctx); |
||||||
|
|
||||||
|
bool done = false; |
||||||
|
while (!done) { |
||||||
|
// Compare and swap loop:
|
||||||
|
// - take a reference to the current index
|
||||||
|
gpr_mu_lock(&g_mu); |
||||||
|
gpr_avl index = gpr_avl_ref(g_subchannel_index); |
||||||
|
gpr_mu_unlock(&g_mu); |
||||||
|
|
||||||
|
// Check to see if this key still refers to the previously
|
||||||
|
// registered subchannel
|
||||||
|
grpc_subchannel *c = gpr_avl_get(index, key); |
||||||
|
if (c != constructed) { |
||||||
|
gpr_avl_unref(index); |
||||||
|
break; |
||||||
|
} |
||||||
|
|
||||||
|
// compare and swap the update (some other thread may have
|
||||||
|
// mutated the index behind us)
|
||||||
|
gpr_avl updated = gpr_avl_remove(gpr_avl_ref(index), key); |
||||||
|
|
||||||
|
gpr_mu_lock(&g_mu); |
||||||
|
if (index.root == g_subchannel_index.root) { |
||||||
|
GPR_SWAP(gpr_avl, updated, g_subchannel_index); |
||||||
|
done = true; |
||||||
|
} |
||||||
|
gpr_mu_unlock(&g_mu); |
||||||
|
|
||||||
|
gpr_avl_unref(updated); |
||||||
|
gpr_avl_unref(index); |
||||||
|
} |
||||||
|
|
||||||
|
leave_ctx(exec_ctx); |
||||||
|
} |
||||||
@ -0,0 +1,77 @@ |
|||||||
|
/*
|
||||||
|
* |
||||||
|
* Copyright 2016, Google Inc. |
||||||
|
* All rights reserved. |
||||||
|
* |
||||||
|
* Redistribution and use in source and binary forms, with or without |
||||||
|
* modification, are permitted provided that the following conditions are |
||||||
|
* met: |
||||||
|
* |
||||||
|
* * Redistributions of source code must retain the above copyright |
||||||
|
* notice, this list of conditions and the following disclaimer. |
||||||
|
* * Redistributions in binary form must reproduce the above |
||||||
|
* copyright notice, this list of conditions and the following disclaimer |
||||||
|
* in the documentation and/or other materials provided with the |
||||||
|
* distribution. |
||||||
|
* * Neither the name of Google Inc. nor the names of its |
||||||
|
* contributors may be used to endorse or promote products derived from |
||||||
|
* this software without specific prior written permission. |
||||||
|
* |
||||||
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
||||||
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
||||||
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
||||||
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
||||||
|
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
||||||
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
||||||
|
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
||||||
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
||||||
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
||||||
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
||||||
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||||||
|
* |
||||||
|
*/ |
||||||
|
|
||||||
|
#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_INDEX_H |
||||||
|
#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_INDEX_H |
||||||
|
|
||||||
|
#include "src/core/client_config/connector.h" |
||||||
|
#include "src/core/client_config/subchannel.h" |
||||||
|
|
||||||
|
/** \file Provides an index of active subchannels so that they can be
|
||||||
|
shared amongst channels */ |
||||||
|
|
||||||
|
typedef struct grpc_subchannel_key grpc_subchannel_key; |
||||||
|
|
||||||
|
/** Create a key that can be used to uniquely identify a subchannel */ |
||||||
|
grpc_subchannel_key *grpc_subchannel_key_create(grpc_connector *con, |
||||||
|
grpc_subchannel_args *args); |
||||||
|
|
||||||
|
/** Destroy a subchannel key */ |
||||||
|
void grpc_subchannel_key_destroy(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key); |
||||||
|
|
||||||
|
/** Given a subchannel key, find the subchannel registered for it.
|
||||||
|
Returns NULL if no such channel exists. |
||||||
|
Thread-safe. */ |
||||||
|
grpc_subchannel *grpc_subchannel_index_find(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key); |
||||||
|
|
||||||
|
/** Register a subchannel against a key.
|
||||||
|
Takes ownership of \a constructed. |
||||||
|
Returns the registered subchannel. This may be different from |
||||||
|
\a constructed in the case of a registration race. */ |
||||||
|
grpc_subchannel *grpc_subchannel_index_register(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key, |
||||||
|
grpc_subchannel *constructed); |
||||||
|
|
||||||
|
/** Remove \a constructed as the registered subchannel for \a key. */ |
||||||
|
void grpc_subchannel_index_unregister(grpc_exec_ctx *exec_ctx, |
||||||
|
grpc_subchannel_key *key, |
||||||
|
grpc_subchannel *constructed); |
||||||
|
|
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/** Initialize the subchannel index (global) */ |
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|
void grpc_subchannel_index_init(void); |
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|
/** Shutdown the subchannel index (global) */ |
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void grpc_subchannel_index_shutdown(void); |
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#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_INDEX_H */ |
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