Add explanation for recv_state

pull/12137/head
Yuchen Zeng 8 years ago
parent e40e259dd1
commit 6eb505b305
  1. 38
      src/core/lib/surface/call.c

@ -144,6 +144,9 @@ typedef struct {
grpc_call *sibling_prev;
} child_call;
#define RECV_NONE ((gpr_atm)0)
#define RECV_INITIAL_METADATA_FIRST ((gpr_atm)1)
struct grpc_call {
gpr_refcount ext_ref;
gpr_arena *arena;
@ -223,10 +226,23 @@ struct grpc_call {
} server;
} final_op;
// Either 0 (no initial metadata and messages received),
// 1 (received initial metadata first)
// or a batch_control* (received messages first, the lowest bit is 0)
gpr_atm saved_receiving_stream_ready_bctlp;
/* recv_state can contain one of the following values:
RECV_NONE : : no initial metadata and messages received
RECV_INITIAL_METADATA_FIRST : received initial metadata first
a batch_control* : received messages first
+------1------RECV_NONE------3-----+
| |
| |
v v
RECV_INITIAL_METADATA_FIRST receiving_stream_ready_bctlp
| ^ | ^
| | | |
+-----2-----+ +-----4-----+
For 1, 4: See receiving_initial_metadata_ready() function
For 2, 3: See receiving_stream_ready() function */
gpr_atm recv_state;
};
grpc_tracer_flag grpc_call_error_trace =
@ -1290,12 +1306,11 @@ static void receiving_stream_ready(grpc_exec_ctx *exec_ctx, void *bctlp,
cancel_with_error(exec_ctx, call, STATUS_FROM_SURFACE,
GRPC_ERROR_REF(error));
}
/* If saved_receiving_stream_ready_bctlp is 0, we will save the batch_control
/* If recv_state is RECV_NONE, we will save the batch_control
* object with rel_cas, and will not use it after the cas. Its corresponding
* acq_load is in receiving_initial_metadata_ready() */
if (error != GRPC_ERROR_NONE || call->receiving_stream == NULL ||
!gpr_atm_rel_cas(&call->saved_receiving_stream_ready_bctlp, 0,
(gpr_atm)bctlp)) {
!gpr_atm_rel_cas(&call->recv_state, RECV_NONE, (gpr_atm)bctlp)) {
process_data_after_md(exec_ctx, bctlp);
}
}
@ -1388,8 +1403,7 @@ static void receiving_initial_metadata_ready(grpc_exec_ctx *exec_ctx,
grpc_closure *saved_rsr_closure = NULL;
while (true) {
gpr_atm rsr_bctlp =
gpr_atm_acq_load(&call->saved_receiving_stream_ready_bctlp);
gpr_atm rsr_bctlp = gpr_atm_acq_load(&call->recv_state);
/* Should only receive initial metadata once */
GPR_ASSERT(rsr_bctlp != 1);
if (rsr_bctlp == 0) {
@ -1398,8 +1412,8 @@ static void receiving_initial_metadata_ready(grpc_exec_ctx *exec_ctx,
* no_barrier_cas is used, as this function won't access the batch_control
* object saved by receiving_stream_ready() if the initial metadata is
* received first. */
if (gpr_atm_no_barrier_cas(&call->saved_receiving_stream_ready_bctlp, 0,
1)) {
if (gpr_atm_no_barrier_cas(&call->recv_state, RECV_NONE,
RECV_INITIAL_METADATA_FIRST)) {
break;
}
} else {
@ -1407,7 +1421,7 @@ static void receiving_initial_metadata_ready(grpc_exec_ctx *exec_ctx,
saved_rsr_closure = GRPC_CLOSURE_CREATE(receiving_stream_ready,
(batch_control *)rsr_bctlp,
grpc_schedule_on_exec_ctx);
/* No need to modify saved_receiving_stream_ready_bctlp */
/* No need to modify recv_state */
break;
}
}

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