mirror of https://github.com/grpc/grpc.git
Vijay Pai
10 years ago
parent
a4ae29bb91
commit
005e305c22
10 changed files with 204 additions and 0 deletions
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/*
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* |
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* Copyright 2015, 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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#include "src/core/support/stack_lockfree.h" |
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#include <stdlib.h> |
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#include <string.h> |
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#include <grpc/support/port_platform.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/log.h> |
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/* The lockfree node structure is a single architecture-level
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word that allows for an atomic CAS to set it up. */ |
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struct lockfree_node_contents { |
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/* next thing to look at. Actual index for head, next index otherwise */ |
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gpr_uint16 index; |
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#ifdef GPR_ARCH_64 |
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gpr_uint16 pad; |
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gpr_uint32 aba_ctr; |
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#else |
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#ifdef GPR_ARCH_32 |
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gpr_uint16 aba_ctr; |
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#else |
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#error Unsupported bit width architecture |
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#endif |
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#endif |
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}; |
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/* Use a union to make sure that these are in the same bits as an atm word */ |
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typedef union lockfree_node { |
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gpr_atm atm; |
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struct lockfree_node_contents contents; |
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} lockfree_node; |
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#define ENTRY_ALIGNMENT_BITS 3 /* make sure that entries aligned to 8-bytes */ |
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#define INVALID_ENTRY_INDEX ((1<<16)-1) /* reserve this entry as invalid */ |
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struct gpr_stack_lockfree { |
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lockfree_node *entries; |
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lockfree_node head; /* An atomic entry describing curr head */ |
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}; |
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gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) { |
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gpr_stack_lockfree *stack; |
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stack = gpr_malloc(sizeof(*stack)); |
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/* Since we only allocate 16 bits to represent an entry number,
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* make sure that we are within the desired range */ |
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/* Reserve the highest entry number as a dummy */ |
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GPR_ASSERT(entries < INVALID_ENTRY_INDEX); |
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stack->entries = gpr_malloc_aligned(entries * sizeof(stack->entries[0]), |
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ENTRY_ALIGNMENT_BITS); |
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/* Clear out all entries */ |
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memset(stack->entries, 0, entries * sizeof(stack->entries[0])); |
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/* Point the head at reserved dummy entry */ |
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stack->head.contents.index = INVALID_ENTRY_INDEX; |
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return stack; |
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} |
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void gpr_stack_lockfree_destroy(gpr_stack_lockfree *stack) { |
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gpr_free_aligned(stack->entries); |
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gpr_free(stack); |
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} |
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void gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) { |
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lockfree_node head; |
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lockfree_node newhead; |
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/* First fill in the entry's index and aba ctr for new head */ |
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newhead.contents.index = (gpr_uint16)entry; |
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/* Also post-increment the aba_ctr */ |
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newhead.contents.aba_ctr = stack->entries[entry].contents.aba_ctr++; |
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do { |
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/* Atomically get the existing head value for use */ |
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head.atm = gpr_atm_no_barrier_load(&(stack->head.atm)); |
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/* Point to it */ |
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stack->entries[entry].contents.index = head.contents.index; |
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} while (!gpr_atm_rel_cas(&(stack->head.atm), |
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head.atm, newhead.atm)); |
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/* Use rel_cas above to make sure that entry index is set properly */ |
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} |
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int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) { |
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lockfree_node head; |
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lockfree_node newhead; |
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do { |
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head.atm = gpr_atm_acq_load(&(stack->head.atm)); |
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if (head.contents.index == INVALID_ENTRY_INDEX) { |
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return -1; |
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} |
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newhead.contents.index = stack->entries[head.contents.index].contents.index; |
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} while (!gpr_atm_no_barrier_cas(&(stack->head.atm), |
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head.atm, |
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newhead.atm)); |
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return newhead.contents.index; |
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} |
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@ -0,0 +1,50 @@ |
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/*
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* |
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* Copyright 2015, 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, |
||||
* 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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#ifndef GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H |
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#define GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H |
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typedef struct gpr_stack_lockfree gpr_stack_lockfree; |
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/* This stack must specify the maximum number of entries to track.
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The current implementation only allows up to 65534 entries */ |
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gpr_stack_lockfree *gpr_stack_lockfree_create(int entries); |
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void gpr_stack_lockfree_destroy(gpr_stack_lockfree *); |
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/* Pass in a valid entry number for the next stack entry */ |
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void gpr_stack_lockfree_push(gpr_stack_lockfree *, int entry); |
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/* Returns -1 on empty or the actual entry number */ |
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int gpr_stack_lockfree_pop(gpr_stack_lockfree *); |
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#endif /* GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H */ |
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