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