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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMECAST_CRASH_LINUX_SYNCHRONIZED_MINIDUMP_MANAGER_H_
#define CHROMECAST_CRASH_LINUX_SYNCHRONIZED_MINIDUMP_MANAGER_H_
#include <vector>
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/values.h"
#include "chromecast/crash/linux/dump_info.h"
namespace chromecast {
// Abstract base class for mutually-exclusive minidump handling. Ensures
// synchronized access among instances of this class to the minidumps directory
// using a file lock. The "lockfile" also holds serialized metadata about each
// of the minidumps in the directory. Derived classes should not access the
// lockfile directly. Instead, use protected methods to query and modify the
// metadata, but only within the implementation of DoWork().
//
// This class holds an in memory representation of the lockfile and metadata
// file when the lockfile is held. Modifier methods work on this in memory
// representation. When the lockfile is released, the in memory representations
// are written to file
//
// The lockfile file is of the following format:
// { <dump_info1> }
// { <dump_info2> }
// ...
// { <dump_infoN> }
//
// Note that this isn't a valid json object. It is formatted in this way so
// that producers to this file do not need to understand json.
//
// Current external producers:
// + watchdog
//
//
// The metadata file is a separate file containing a json dictionary.
//
class SynchronizedMinidumpManager {
public:
// Length of a ratelimit period in seconds.
static const int kRatelimitPeriodSeconds;
// Number of dumps allowed per period.
static const int kRatelimitPeriodMaxDumps;
virtual ~SynchronizedMinidumpManager();
protected:
SynchronizedMinidumpManager();
// Acquires the lock, calls DoWork(), then releases the lock when DoWork()
// returns. Derived classes should expose a method which calls this. Returns
// the status of DoWork(), or false if the lock was not successfully acquired.
bool AcquireLockAndDoWork();
// Derived classes must implement this method. It will be called from
// DoWorkLocked after the lock has been successfully acquired. The lockfile
// shall be accessed and mutated only through the methods below. All other
// files shall be managed as needed by the derived class.
virtual bool DoWork() = 0;
// Get the current dumps in the lockfile.
std::vector<std::unique_ptr<DumpInfo>> GetDumps();
// Set |dumps| as the dumps in |lockfile_|, replacing current list of dumps.
bool SetCurrentDumps(const std::vector<std::unique_ptr<DumpInfo>>& dumps);
// Serialize |dump_info| and append it to the lockfile. Note that the child
// class must only call this inside DoWork(). This should be the only method
// used to write to the lockfile. Only call this if the minidump has been
// generated in the minidumps directory successfully. Returns true on success,
// false otherwise.
bool AddEntryToLockFile(const DumpInfo& dump_info);
// Remove the lockfile entry at |index| in the current in memory
// representation of the lockfile. If the index is invalid returns false,
// otherwise returns true.
bool RemoveEntryFromLockFile(int index);
// Get the number of un-uploaded dumps in the dump_path directory.
// If delete_all_dumps is true, also delete all these files, this is used to
// clean lingering dump files.
int GetNumDumps(bool delete_all_dumps);
// Increment the number of dumps in the current ratelimit period.
// Returns true on success, false on error.
bool IncrementNumDumpsInCurrentPeriod();
// Decrement the number of dumps in the current ratelimit period.
// Returns true on success, false on error.
bool DecrementNumDumpsInCurrentPeriod();
// Start a new rate-limit period, thus allowing crash uploads to proceed.
void ResetRateLimitPeriod();
// Returns true when dumps uploaded in current rate limit period is less than
// |kRatelimitPeriodMaxDumps|. Resets rate limit period if period time has
// elapsed.
bool CanUploadDump();
// Returns true when there are dumps in the lockfile or extra files in the
// dump directory, false otherwise.
// Used to avoid unnecessary file locks in consumers.
bool HasDumps();
// Ensures that the lockfile and metadata are in a valid state. This requires
// obtaining the lockfile. Will fail if lockfile already held.
bool InitializeFileState();
// Cached path for the minidumps directory.
const base::FilePath dump_path_;
private:
// Acquire the lock file. Blocks if another process holds it, or if called
// a second time by the same process. Returns true if successful, or false
// otherwise.
bool AcquireLockFile();
// Parse the lockfile and metadata file, populating |dumps_| and |metadata_|
// for modifier functions to use. Returns false if an error occurred,
// otherwise returns true. This must not be called unless |this| has acquired
// the lock.
bool ParseFiles();
// Write deserialized |dumps| to |lockfile_path_| and the deserialized
// |metadata| to |metadata_path_|.
bool WriteFiles(const base::ListValue* dumps, const base::Value* metadata);
// Creates an empty lock file and an initialized metadata file.
bool InitializeFiles();
// Release the lock file with the associated *fd*.
void ReleaseLockFile();
const base::FilePath lockfile_path_;
const base::FilePath metadata_path_;
int lockfile_fd_;
std::unique_ptr<base::Value> metadata_;
std::unique_ptr<base::ListValue> dumps_;
DISALLOW_COPY_AND_ASSIGN(SynchronizedMinidumpManager);
};
} // namespace chromecast
#endif // CHROMECAST_CRASH_LINUX_SYNCHRONIZED_MINIDUMP_MANAGER_H_