[Binder Tansport] Move trans stream receiver callbacks out of `mu_` (#32438)

This prevents deadlock against wire writer issues.

Currently, there are some `transport_stream_receiver_` callbacks
triggered by NDK binder may acquire `WireReaderImpl::mu_` first then
`WireWriterImpl::write_mu_`. We don't like see this.

We have this problem since some client and server are in the same
process. The behavior of NDK binder seems more aggressive when the Tx
and Rx are in the same process.

BUILD

@@ -1013,6 +1013,7 @@ grpc_cc_library(
         "absl/base:core_headers",
         "absl/cleanup",
         "absl/container:flat_hash_map",
+        "absl/functional:any_invocable",
         "absl/hash",
         "absl/memory",
         "absl/meta:type_traits",

src/core/ext/transport/binder/wire_format/wire_reader_impl.cc

@@ -24,6 +24,7 @@
 #include <utility>
 #include <vector>
 
+#include "absl/functional/any_invocable.h"
 #include "absl/memory/memory.h"
 #include "absl/status/statusor.h"
 
@@ -248,29 +249,45 @@ absl::Status WireReaderImpl::ProcessStreamingTransaction(
     transaction_code_t code, ReadableParcel* parcel) {
   bool need_to_send_ack = false;
   int64_t num_bytes = 0;
+  // Indicates which callbacks should be cancelled. It will be initialized as
+  // the flags the in-coming transaction carries, and when a particular
+  // callback is completed, the corresponding bit in cancellation_flag will be
+  // set to 0 so that we won't cancel it afterward.
+  int cancellation_flags = 0;
+  // The queue saves the actions needed to be done "WITHOUT" `mu_`.
+  // It prevents deadlock against wire writer issues.
+  std::queue<absl::AnyInvocable<void() &&>> deferred_func_queue;
   absl::Status tx_process_result;
+
   {
     grpc_core::MutexLock lock(&mu_);
     if (!connected_) {
       return absl::InvalidArgumentError("Transports not connected yet");
     }
 
-    // Indicate which callbacks should be cancelled. It will be initialized as
-    // the flags the in-coming transaction carries, and when a particular
-    // callback is completed, the corresponding bit in cancellation_flag will be
-    // set to 0 so that we won't cancel it afterward.
-    int cancellation_flags = 0;
-    tx_process_result =
-        ProcessStreamingTransactionImpl(code, parcel, &cancellation_flags);
+    tx_process_result = ProcessStreamingTransactionImpl(
+        code, parcel, &cancellation_flags, deferred_func_queue);
+    if ((num_incoming_bytes_ - num_acknowledged_bytes_) >=
+        kFlowControlAckBytes) {
+      need_to_send_ack = true;
+      num_bytes = num_incoming_bytes_;
+      num_acknowledged_bytes_ = num_incoming_bytes_;
+    }
+  }
+  // Executes all actions in the queue.
+  while (!deferred_func_queue.empty()) {
+    std::move(deferred_func_queue.front())();
+    deferred_func_queue.pop();
+  }
+
   if (!tx_process_result.ok()) {
     gpr_log(GPR_ERROR, "Failed to process streaming transaction: %s",
             tx_process_result.ToString().c_str());
-      // Something went wrong when receiving transaction. Cancel failed
-      // requests.
+    // Something went wrong when receiving transaction. Cancel failed requests.
     if (cancellation_flags & kFlagPrefix) {
       gpr_log(GPR_INFO, "cancelling initial metadata");
-        transport_stream_receiver_->NotifyRecvInitialMetadata(
-            code, tx_process_result);
+      transport_stream_receiver_->NotifyRecvInitialMetadata(code,
+                                                            tx_process_result);
     }
     if (cancellation_flags & kFlagMessageData) {
       gpr_log(GPR_INFO, "cancelling message data");
@@ -282,13 +299,7 @@ absl::Status WireReaderImpl::ProcessStreamingTransaction(
           code, tx_process_result, 0);
     }
   }
-    if ((num_incoming_bytes_ - num_acknowledged_bytes_) >=
-        kFlowControlAckBytes) {
-      need_to_send_ack = true;
-      num_bytes = num_incoming_bytes_;
-      num_acknowledged_bytes_ = num_incoming_bytes_;
-    }
-  }
+
   if (need_to_send_ack) {
     if (!wire_writer_ready_notification_.WaitForNotificationWithTimeout(
             absl::Seconds(5))) {
@@ -310,7 +321,8 @@ absl::Status WireReaderImpl::ProcessStreamingTransaction(
 }
 
 absl::Status WireReaderImpl::ProcessStreamingTransactionImpl(
-    transaction_code_t code, ReadableParcel* parcel, int* cancellation_flags) {
+    transaction_code_t code, ReadableParcel* parcel, int* cancellation_flags,
+    std::queue<absl::AnyInvocable<void() &&>>& deferred_func_queue) {
   GPR_ASSERT(cancellation_flags);
   num_incoming_bytes_ += parcel->GetDataSize();
   gpr_log(GPR_INFO, "Total incoming bytes: %" PRId64, num_incoming_bytes_);
@@ -380,8 +392,12 @@ absl::Status WireReaderImpl::ProcessStreamingTransactionImpl(
                                                 "binder.authority");
       }
     }
-    transport_stream_receiver_->NotifyRecvInitialMetadata(
-        code, *initial_metadata_or_error);
+    deferred_func_queue.emplace([this, code,
+                                 initial_metadata_or_error = std::move(
+                                     initial_metadata_or_error)]() mutable {
+      this->transport_stream_receiver_->NotifyRecvInitialMetadata(
+          code, std::move(initial_metadata_or_error));
+    });
     *cancellation_flags &= ~kFlagPrefix;
   }
   if (flags & kFlagMessageData) {
@@ -396,7 +412,9 @@ absl::Status WireReaderImpl::ProcessStreamingTransactionImpl(
     if ((flags & kFlagMessageDataIsPartial) == 0) {
       std::string s = std::move(message_buffer_[code]);
       message_buffer_.erase(code);
-      transport_stream_receiver_->NotifyRecvMessage(code, std::move(s));
+      deferred_func_queue.emplace([this, code, s = std::move(s)]() mutable {
+        this->transport_stream_receiver_->NotifyRecvMessage(code, std::move(s));
+      });
     }
     *cancellation_flags &= ~kFlagMessageData;
   }
@@ -416,8 +434,12 @@ absl::Status WireReaderImpl::ProcessStreamingTransactionImpl(
       }
       trailing_metadata = *trailing_metadata_or_error;
     }
-    transport_stream_receiver_->NotifyRecvTrailingMetadata(
+    deferred_func_queue.emplace(
+        [this, code, trailing_metadata = std::move(trailing_metadata),
+         status]() mutable {
+          this->transport_stream_receiver_->NotifyRecvTrailingMetadata(
               code, std::move(trailing_metadata), status);
+        });
     *cancellation_flags &= ~kFlagSuffix;
   }
   return absl::OkStatus();

src/core/ext/transport/binder/wire_format/wire_reader_impl.h

@@ -18,9 +18,11 @@
 #include <grpc/support/port_platform.h>
 
 #include <memory>
+#include <queue>
 #include <utility>
 
 #include "absl/container/flat_hash_map.h"
+#include "absl/functional/any_invocable.h"
 
 #include <grpcpp/security/binder_security_policy.h>
 
@@ -99,9 +101,11 @@ class WireReaderImpl : public WireReader {
  private:
   absl::Status ProcessStreamingTransaction(transaction_code_t code,
                                            ReadableParcel* parcel);
-  absl::Status ProcessStreamingTransactionImpl(transaction_code_t code,
-                                               ReadableParcel* parcel,
-                                               int* cancellation_flags)
+  absl::Status ProcessStreamingTransactionImpl(
+      transaction_code_t code, ReadableParcel* parcel, int* cancellation_flags,
+      // The queue saves the actions needed to be done "WITHOUT" `mu_`.
+      // It prevents deadlock against wire writer issues.
+      std::queue<absl::AnyInvocable<void() &&>>& deferred_func_queue)
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(mu_);
 
   std::shared_ptr<TransportStreamReceiver> transport_stream_receiver_;