platform_system_core/logd/FlushCommand.cpp

/*
 * Copyright (C) 2012-2014 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 <stdlib.h>

#include "FlushCommand.h"
#include "LogBufferElement.h"
#include "LogCommand.h"
#include "LogReader.h"
#include "LogTimes.h"
#include "LogUtils.h"

FlushCommand::FlushCommand(LogReader &reader,
                           bool nonBlock,
                           unsigned long tail,
                           unsigned int logMask,
                           pid_t pid,
                           uint64_t start,
                           uint64_t timeout) :
        mReader(reader),
        mNonBlock(nonBlock),
        mTail(tail),
        mLogMask(logMask),
        mPid(pid),
        mStart(start),
        mTimeout((start > 1) ? timeout : 0) {
}

// runSocketCommand is called once for every open client on the
// log reader socket. Here we manage and associated the reader
// client tracking and log region locks LastLogTimes list of
// LogTimeEntrys, and spawn a transitory per-client thread to
// work at filing data to the  socket.
//
// global LogTimeEntry::lock() is used to protect access,
// reference counts are used to ensure that individual
// LogTimeEntry lifetime is managed when not protected.
void FlushCommand::runSocketCommand(SocketClient *client) {
    LogTimeEntry *entry = NULL;
    LastLogTimes &times = mReader.logbuf().mTimes;

    LogTimeEntry::lock();
    LastLogTimes::iterator it = times.begin();
    while(it != times.end()) {
        entry = (*it);
        if (entry->mClient == client) {
            if (entry->mTimeout.tv_sec || entry->mTimeout.tv_nsec) {
                LogTimeEntry::unlock();
                return;
            }
            entry->triggerReader_Locked();
            if (entry->runningReader_Locked()) {
                LogTimeEntry::unlock();
                return;
            }
            entry->incRef_Locked();
            break;
        }
        it++;
    }

    if (it == times.end()) {
        // Create LogTimeEntry in notifyNewLog() ?
        if (mTail == (unsigned long) -1) {
            LogTimeEntry::unlock();
            return;
        }
        entry = new LogTimeEntry(mReader, client, mNonBlock, mTail, mLogMask,
                                 mPid, mStart, mTimeout);
        times.push_front(entry);
    }

    client->incRef();

    // release client and entry reference counts once done
    entry->startReader_Locked();
    LogTimeEntry::unlock();
}

bool FlushCommand::hasReadLogs(SocketClient *client) {
    return clientHasLogCredentials(client);
}