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/*
* Copyright (C) 2017 The Android Open Source Project
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "logd/LogReader.h"
#include "guardrail/StatsdStats.h"
#include <time.h>
#include <unistd.h>
#include <utils/Errors.h>
using namespace android;
using namespace std;
namespace android {
namespace os {
namespace statsd {
#define SNOOZE_INITIAL_MS 100
#define SNOOZE_MAX_MS (10 * 60 * 1000) // Ten minutes
LogReader::LogReader(const sp<LogListener>& listener) : mListener(listener) {
}
LogReader::~LogReader() {
}
void LogReader::Run() {
int nextSnoozeMs = SNOOZE_INITIAL_MS;
// In an ideal world, this outer loop will only ever run one iteration, but it
// exists to handle crashes in logd. The inner loop inside connect_and_read()
// reads from logd forever, but if that read fails, we fall out to the outer
// loop, do the backoff (resetting the backoff timeout if we successfully read
// something), and then try again.
while (true) {
// Connect and read
int lineCount = connect_and_read();
// Figure out how long to sleep.
if (lineCount > 0) {
// If we managed to read at least one line, reset the backoff
nextSnoozeMs = SNOOZE_INITIAL_MS;
} else {
// Otherwise, expontial backoff
nextSnoozeMs *= 1.5f;
if (nextSnoozeMs > 10 * 60 * 1000) {
// Don't wait for toooo long.
nextSnoozeMs = SNOOZE_MAX_MS;
}
}
// Sleep
timespec ts;
timespec rem;
ts.tv_sec = nextSnoozeMs / 1000;
ts.tv_nsec = (nextSnoozeMs % 1000) * 1000000L;
while (nanosleep(&ts, &rem) == -1) {
if (errno == EINTR) {
ts = rem;
}
// other errors are basically impossible
}
}
}
int LogReader::connect_and_read() {
int lineCount = 0;
status_t err;
logger_list* loggers;
logger* eventLogger;
// Prepare the logging context
loggers = android_logger_list_alloc(ANDROID_LOG_RDONLY,
/* don't stop after N lines */ 0,
/* no pid restriction */ 0);
// Open the buffer(s)
eventLogger = android_logger_open(loggers, LOG_ID_STATS);
// Read forever
if (eventLogger) {
log_msg msg;
while (true) {
// Read a message
err = android_logger_list_read(loggers, &msg);
// err = 0 - no content, unexpected connection drop or EOF.
// err = +ive number - size of retrieved data from logger
// err = -ive number, OS supplied error _except_ for -EAGAIN
if (err <= 0) {
StatsdStats::getInstance().noteLoggerError(err);
fprintf(stderr, "logcat read failure: %s\n", strerror(err));
break;
}
// Record that we read one (used above to know how to snooze).
lineCount++;
// Wrap it in a LogEvent object
LogEvent event(msg);
// Call the listener
mListener->OnLogEvent(&event,
lineCount == 1 /* indicate whether it's a new connection */);
}
}
// Free the logger list and close the individual loggers
android_logger_list_free(loggers);
return lineCount;
}
} // namespace statsd
} // namespace os
} // namespace android
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