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* Copyright 2018 gRPC authors.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <grpc/support/port_platform.h>
#include "absl/types/optional.h"
#include <grpc/support/time.h>
#include "src/core/lib/gprpp/memory.h"
#include "src/core/lib/iomgr/error.h"
#include "src/core/lib/iomgr/internal_errqueue.h"
#include "src/core/lib/iomgr/port.h"
namespace grpc_core {
struct ConnectionMetrics {
/* Delivery rate in Bytes/s. */
absl::optional<uint64_t> delivery_rate;
/* If the delivery rate is limited by the application, this is set to true. */
absl::optional<bool> is_delivery_rate_app_limited;
/* Total packets retransmitted. */
absl::optional<uint32_t> packet_retx;
/* Total packets retransmitted spuriously. This metric is smaller than or
equal to packet_retx. */
absl::optional<uint32_t> packet_spurious_retx;
/* Total packets sent. */
absl::optional<uint32_t> packet_sent;
/* Total packets delivered. */
absl::optional<uint32_t> packet_delivered;
/* Total packets delivered with ECE marked. This metric is smaller than or
equal to packet_delivered. */
absl::optional<uint32_t> packet_delivered_ce;
/* Total bytes lost so far. */
absl::optional<uint64_t> data_retx;
/* Total bytes sent so far. */
absl::optional<uint64_t> data_sent;
/* Total bytes in write queue but not sent. */
absl::optional<uint64_t> data_notsent;
/* Pacing rate of the connection in Bps */
absl::optional<uint64_t> pacing_rate;
/* Minimum RTT observed in usec. */
absl::optional<uint32_t> min_rtt;
/* Smoothed RTT in usec */
absl::optional<uint32_t> srtt;
/* Send congestion window. */
absl::optional<uint32_t> congestion_window;
/* Slow start threshold in packets. */
absl::optional<uint32_t> snd_ssthresh;
/* Maximum degree of reordering (i.e., maximum number of packets reodered)
on the connection. */
absl::optional<uint32_t> reordering;
/* Represents the number of recurring retransmissions of the first sequence
that is not acknowledged yet. */
absl::optional<uint8_t> recurring_retrans;
/* The cumulative time (in usec) that the transport protocol was busy
sending data. */
absl::optional<uint64_t> busy_usec;
/* The cumulative time (in usec) that the transport protocol was limited by
the receive window size. */
absl::optional<uint64_t> rwnd_limited_usec;
/* The cumulative time (in usec) that the transport protocol was limited by
the send buffer size. */
absl::optional<uint64_t> sndbuf_limited_usec;
struct BufferTimestamp {
gpr_timespec time;
ConnectionMetrics metrics; /* Metrics collected with this timestamp */
struct Timestamps {
BufferTimestamp sendmsg_time;
BufferTimestamp scheduled_time;
BufferTimestamp sent_time;
BufferTimestamp acked_time;
uint32_t byte_offset; /* byte offset relative to the start of the RPC */
tcp_info info; /* tcp_info collected on sendmsg */
/** TracedBuffer is a class to keep track of timestamps for a specific buffer in
* the TCP layer. We are only tracking timestamps for Linux kernels and hence
* this class would only be used by Linux platforms. For all other platforms,
* TracedBuffer would be an empty class.
* The timestamps collected are according to Timestamps declared
* above.
* A TracedBuffer list is kept track of using the head element of the list. If
* the head element of the list is nullptr, then the list is empty.
class TracedBuffer {
/** Use AddNewEntry function instead of using this directly. */
TracedBuffer(uint32_t seq_no, void* arg)
: seq_no_(seq_no), arg_(arg), next_(nullptr) {}
/** Add a new entry in the TracedBuffer list pointed to by head. Also saves
* sendmsg_time with the current timestamp. */
static void AddNewEntry(TracedBuffer** head, uint32_t seq_no, int fd,
void* arg);
/** Processes a received timestamp based on sock_extended_err and
* scm_timestamping structures. It will invoke the timestamps callback if the
* timestamp type is SCM_TSTAMP_ACK. */
static void ProcessTimestamp(TracedBuffer** head,
struct sock_extended_err* serr,
struct cmsghdr* opt_stats,
struct scm_timestamping* tss);
/** Cleans the list by calling the callback for each traced buffer in the list
* with timestamps that it has. */
static void Shutdown(TracedBuffer** head, void* remaining,
grpc_error_handle shutdown_err);
uint32_t seq_no_; /* The sequence number for the last byte in the buffer */
void* arg_; /* The arg to pass to timestamps_callback */
Timestamps ts_; /* The timestamps corresponding to this buffer */
TracedBuffer* next_; /* The next TracedBuffer in the list */
class TracedBuffer {
/* Phony shutdown function */
static void Shutdown(TracedBuffer** /*head*/, void* /*remaining*/,
grpc_error_handle shutdown_err) {
/** Sets the callback function to call when timestamps for a write are
* collected. The callback does not own a reference to error. */
void grpc_tcp_set_write_timestamps_callback(
void (*fn)(void*, Timestamps*, grpc_error_handle error));
} /* namespace grpc_core */