logd/FlushCommand.cpp

/*
 * Copyright (C) 2012-2013 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 <private/android_filesystem_config.h>
#include "FlushCommand.h"
#include "LogBufferElement.h"
#include "LogTimes.h"
#include "LogReader.h"

FlushCommand::FlushCommand(LogReader &reader,
                           bool nonBlock,
                           unsigned long tail,
                           unsigned int logMask,
                           pid_t pid)
        : mReader(reader)
        , mNonBlock(nonBlock)
        , mTail(tail)
        , mLogMask(logMask)
        , mPid(pid)
{ }

// 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) {
            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);
        times.push_back(entry);
    }

    client->incRef();

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

bool FlushCommand::hasReadLogs(SocketClient *client) {
    return (client->getUid() == AID_ROOT)
            || (client->getGid() == AID_ROOT)
            || (client->getGid() == AID_LOG);
}