diff --git a/include/grpc/grpc.h b/include/grpc/grpc.h index f07f584ef2c2a5bc66f3095bfb9585b152c5deee..cedcee7c5426553748776eb42869f1af9676a813 100644 --- a/include/grpc/grpc.h +++ b/include/grpc/grpc.h @@ -127,6 +127,11 @@ typedef struct { /** Initial sequence number for http2 transports */ #define GRPC_ARG_HTTP2_INITIAL_SEQUENCE_NUMBER \ "grpc.http2.initial_sequence_number" +/** Amount to read ahead on individual streams. Defaults to 64kb, larger + values can help throughput on high-latency connections. + NOTE: at some point we'd like to auto-tune this, and this parameter + will become a no-op. */ +#define GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES "grpc.http2.lookahead_bytes" /** How much memory to use for hpack decoding */ #define GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER \ "grpc.http2.hpack_table_size.decoder" diff --git a/src/core/transport/chttp2/internal.h b/src/core/transport/chttp2/internal.h index 216439549c4e8cf68b7cbea1e8d16855e29f61f6..b2ac8ee9657b8cdb1b8eca59b868766efbdb4eeb 100644 --- a/src/core/transport/chttp2/internal.h +++ b/src/core/transport/chttp2/internal.h @@ -191,6 +191,9 @@ typedef struct { copied to next_stream_id in parsing when parsing commences */ gpr_uint32 next_stream_id; + /** how far to lookahead in a stream? */ + gpr_uint32 stream_lookahead; + /** last received stream id */ gpr_uint32 last_incoming_stream_id; diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c index fdd835def93276fd21c2b7f622784d7b4eed12fb..77c68c9df0692ef638841fc9c9048e06f3239acc 100644 --- a/src/core/transport/chttp2_transport.c +++ b/src/core/transport/chttp2_transport.c @@ -52,7 +52,6 @@ #include "src/core/transport/transport_impl.h" #define DEFAULT_WINDOW 65535 -#define GRPC_CHTTP2_STREAM_LOOKAHEAD DEFAULT_WINDOW #define DEFAULT_CONNECTION_WINDOW_TARGET (1024 * 1024) #define MAX_WINDOW 0x7fffffffu @@ -245,6 +244,7 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t, t->global.is_client = is_client; t->writing.outgoing_window = DEFAULT_WINDOW; t->parsing.incoming_window = DEFAULT_WINDOW; + t->global.stream_lookahead = DEFAULT_WINDOW; t->global.connection_window_target = DEFAULT_CONNECTION_WINDOW_TARGET; t->global.ping_counter = 1; t->global.pings.next = t->global.pings.prev = &t->global.pings; @@ -338,6 +338,18 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t, t->global.next_stream_id = (gpr_uint32)channel_args->args[i].value.integer; } + } else if (0 == strcmp(channel_args->args[i].key, + GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES)) { + if (channel_args->args[i].type != GRPC_ARG_INTEGER) { + gpr_log(GPR_ERROR, "%s: must be an integer", + GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES); + } else if (channel_args->args[i].value.integer <= 5) { + gpr_log(GPR_ERROR, "%s: must be at least 5", + GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES); + } else { + t->global.stream_lookahead = + (gpr_uint32)channel_args->args[i].value.integer; + } } else if (0 == strcmp(channel_args->args[i].key, GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER)) { if (channel_args->args[i].type != GRPC_ARG_INTEGER) { @@ -1404,8 +1416,8 @@ static void incoming_byte_stream_update_flow_control( gpr_uint32 max_recv_bytes; /* clamp max recv hint to an allowable size */ - if (max_size_hint >= GPR_UINT32_MAX - GRPC_CHTTP2_STREAM_LOOKAHEAD) { - max_recv_bytes = GPR_UINT32_MAX - GRPC_CHTTP2_STREAM_LOOKAHEAD; + if (max_size_hint >= GPR_UINT32_MAX - transport_global->stream_lookahead) { + max_recv_bytes = GPR_UINT32_MAX - transport_global->stream_lookahead; } else { max_recv_bytes = (gpr_uint32)max_size_hint; } @@ -1418,8 +1430,9 @@ static void incoming_byte_stream_update_flow_control( } /* add some small lookahead to keep pipelines flowing */ - GPR_ASSERT(max_recv_bytes <= GPR_UINT32_MAX - GRPC_CHTTP2_STREAM_LOOKAHEAD); - max_recv_bytes += GRPC_CHTTP2_STREAM_LOOKAHEAD; + GPR_ASSERT(max_recv_bytes <= + GPR_UINT32_MAX - transport_global->stream_lookahead); + max_recv_bytes += transport_global->stream_lookahead; if (stream_global->max_recv_bytes < max_recv_bytes) { gpr_uint32 add_max_recv_bytes = max_recv_bytes - stream_global->max_recv_bytes;