131 lines
3.3 KiB
C++
131 lines
3.3 KiB
C++
/*
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* Copyright © 2016 Mozilla Foundation
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*
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* This program is made available under an ISC-style license. See the
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* accompanying file LICENSE for details.
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*/
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#define NOMINMAX
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#include "cubeb_log.h"
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#include "cubeb_ringbuffer.h"
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#include <cstdarg>
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <time.h>
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#endif
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cubeb_log_level g_cubeb_log_level;
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cubeb_log_callback g_cubeb_log_callback;
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/** The maximum size of a log message, after having been formatted. */
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const size_t CUBEB_LOG_MESSAGE_MAX_SIZE = 256;
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/** The maximum number of log messages that can be queued before dropping
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* messages. */
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const size_t CUBEB_LOG_MESSAGE_QUEUE_DEPTH = 40;
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/** Number of milliseconds to wait before dequeuing log messages. */
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#define CUBEB_LOG_BATCH_PRINT_INTERVAL_MS 10
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/**
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* This wraps an inline buffer, that represents a log message, that must be
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* null-terminated.
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* This class should not use system calls or other potentially blocking code.
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*/
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class cubeb_log_message
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{
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public:
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cubeb_log_message()
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{
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*storage = '\0';
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}
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cubeb_log_message(char const str[CUBEB_LOG_MESSAGE_MAX_SIZE])
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{
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size_t length = strlen(str);
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/* paranoia against malformed message */
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assert(length < CUBEB_LOG_MESSAGE_MAX_SIZE);
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if (length > CUBEB_LOG_MESSAGE_MAX_SIZE - 1) {
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return;
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}
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PodCopy(storage, str, length);
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storage[length] = '\0';
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}
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char const * get() {
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return storage;
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}
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private:
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char storage[CUBEB_LOG_MESSAGE_MAX_SIZE];
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};
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/** Lock-free asynchronous logger, made so that logging from a
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* real-time audio callback does not block the audio thread. */
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class cubeb_async_logger
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{
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public:
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/* This is thread-safe since C++11 */
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static cubeb_async_logger & get() {
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static cubeb_async_logger instance;
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return instance;
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}
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void push(char const str[CUBEB_LOG_MESSAGE_MAX_SIZE])
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{
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cubeb_log_message msg(str);
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msg_queue.enqueue(msg);
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}
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void run()
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{
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std::thread([this]() {
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while (true) {
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cubeb_log_message msg;
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while (msg_queue.dequeue(&msg, 1)) {
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LOGV("%s", msg.get());
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}
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#ifdef _WIN32
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Sleep(CUBEB_LOG_BATCH_PRINT_INTERVAL_MS);
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#else
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timespec sleep_duration = sleep_for;
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timespec remainder;
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do {
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if (nanosleep(&sleep_duration, &remainder) == 0 ||
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errno != EINTR) {
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break;
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}
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sleep_duration = remainder;
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} while (remainder.tv_sec || remainder.tv_nsec);
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#endif
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}
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}).detach();
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}
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private:
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#ifndef _WIN32
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const struct timespec sleep_for = {
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CUBEB_LOG_BATCH_PRINT_INTERVAL_MS/1000,
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(CUBEB_LOG_BATCH_PRINT_INTERVAL_MS%1000)*1000*1000
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};
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#endif
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cubeb_async_logger()
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: msg_queue(CUBEB_LOG_MESSAGE_QUEUE_DEPTH)
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{
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run();
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}
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/** This is quite a big data structure, but is only instantiated if the
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* asynchronous logger is used.*/
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lock_free_queue<cubeb_log_message> msg_queue;
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};
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void cubeb_async_log(char const * fmt, ...)
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{
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if (!g_cubeb_log_callback) {
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return;
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}
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// This is going to copy a 256 bytes array around, which is fine.
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// We don't want to allocate memory here, because this is made to
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// be called from a real-time callback.
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va_list args;
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va_start(args, fmt);
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char msg[CUBEB_LOG_MESSAGE_MAX_SIZE];
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vsnprintf(msg, CUBEB_LOG_MESSAGE_MAX_SIZE, fmt, args);
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cubeb_async_logger::get().push(msg);
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va_end(args);
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}
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