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/**
* Copyright (c) 2020, 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.
*/
#ifndef WATCHDOG_SERVER_SRC_PROCPIDSTAT_H_
#define WATCHDOG_SERVER_SRC_PROCPIDSTAT_H_
#include <android-base/result.h>
#include <android-base/stringprintf.h>
#include <gtest/gtest_prod.h>
#include <inttypes.h>
#include <stdint.h>
#include <utils/Mutex.h>
#include <utils/RefBase.h>
#include <string>
#include <unordered_map>
#include <vector>
namespace android {
namespace automotive {
namespace watchdog {
using android::base::StringPrintf;
#define PID_FOR_INIT 1
constexpr const char* kProcDirPath = "/proc";
constexpr const char* kStatFileFormat = "/%" PRIu32 "/stat";
constexpr const char* kTaskDirFormat = "/%" PRIu32 "/task";
constexpr const char* kStatusFileFormat = "/%" PRIu32 "/status";
struct PidStat {
uint32_t pid = 0;
std::string comm = "";
std::string state = "";
uint32_t ppid = 0;
uint64_t majorFaults = 0;
uint32_t numThreads = 0;
uint64_t startTime = 0; // Useful when identifying PID/TID reuse
};
struct ProcessStats {
int64_t tgid = -1; // -1 indicates a failure to read this value
int64_t uid = -1; // -1 indicates a failure to read this value
PidStat process = {}; // Aggregated stats across all the threads
std::unordered_map<uint32_t, PidStat> threads; // Per-thread stat including the main thread
};
// Collector/parser for `/proc/[pid]/stat`, `/proc/[pid]/task/[tid]/stat` and /proc/[pid]/status`
// files.
class ProcPidStat : public RefBase {
public:
explicit ProcPidStat(const std::string& path = kProcDirPath) :
mLastProcessStats({}), mPath(path) {
std::string pidStatPath = StringPrintf((mPath + kStatFileFormat).c_str(), PID_FOR_INIT);
std::string tidStatPath = StringPrintf((mPath + kTaskDirFormat + kStatFileFormat).c_str(),
PID_FOR_INIT, PID_FOR_INIT);
std::string pidStatusPath = StringPrintf((mPath + kStatusFileFormat).c_str(), PID_FOR_INIT);
mEnabled = !access(pidStatPath.c_str(), R_OK) && !access(tidStatPath.c_str(), R_OK) &&
!access(pidStatusPath.c_str(), R_OK);
}
virtual ~ProcPidStat() {}
// Collects pid info delta since the last collection.
virtual android::base::Result<std::vector<ProcessStats>> collect();
// Called by IoPerfCollection and tests.
virtual bool enabled() { return mEnabled; }
virtual std::string dirPath() { return mPath; }
private:
// Reads the contents of the below files:
// 1. Pid stat file at |mPath| + |kStatFileFormat|
// 2. Tid stat file at |mPath| + |kTaskDirFormat| + |kStatFileFormat|
android::base::Result<std::unordered_map<uint32_t, ProcessStats>> getProcessStatsLocked() const;
// Reads the tgid and real UID for the given PID from |mPath| + |kStatusFileFormat|.
android::base::Result<void> getPidStatusLocked(ProcessStats* processStats) const;
// Makes sure only one collection is running at any given time.
Mutex mMutex;
// Last dump of per-process stats. Useful for calculating the delta and identifying PID/TID
// reuse.
std::unordered_map<uint32_t, ProcessStats> mLastProcessStats GUARDED_BY(mMutex);
// True if the below files are accessible:
// 1. Pid stat file at |mPath| + |kTaskStatFileFormat|
// 2. Tid stat file at |mPath| + |kTaskDirFormat| + |kStatFileFormat|
// 3. Pid status file at |mPath| + |kStatusFileFormat|
// Otherwise, set to false.
bool mEnabled;
// Proc directory path. Default value is |kProcDirPath|.
// Updated by tests to point to a different location when needed.
std::string mPath;
FRIEND_TEST(IoPerfCollectionTest, TestValidProcPidContents);
FRIEND_TEST(ProcPidStatTest, TestValidStatFiles);
FRIEND_TEST(ProcPidStatTest, TestHandlesProcessTerminationBetweenScanningAndParsing);
FRIEND_TEST(ProcPidStatTest, TestHandlesPidTidReuse);
};
} // namespace watchdog
} // namespace automotive
} // namespace android
#endif // WATCHDOG_SERVER_SRC_PROCPIDSTAT_H_