// 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 BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_
#define BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_

#include <stdint.h>

#include <map>
#include <memory>
#include <unordered_set>
#include <vector>

#include "base/atomicops.h"
#include "base/containers/hash_tables.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/singleton.h"
#include "base/synchronization/lock.h"
#include "base/trace_event/memory_allocator_dump.h"
#include "base/trace_event/memory_dump_provider_info.h"
#include "base/trace_event/memory_dump_request_args.h"
#include "base/trace_event/process_memory_dump.h"
#include "base/trace_event/trace_event.h"

// Forward declare |MemoryDumpManagerDelegateImplTest| so that we can make it a
// friend of |MemoryDumpManager| and give it access to |SetInstanceForTesting|.
namespace memory_instrumentation {

class MemoryDumpManagerDelegateImplTest;

}  // namespace memory_instrumentation

namespace base {

class SingleThreadTaskRunner;
class Thread;

namespace trace_event {

class MemoryDumpManagerDelegate;
class MemoryDumpProvider;
class MemoryDumpSessionState;
class MemoryDumpScheduler;

// This is the interface exposed to the rest of the codebase to deal with
// memory tracing. The main entry point for clients is represented by
// RequestDumpPoint(). The extension by Un(RegisterDumpProvider).
class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
 public:
  static const char* const kTraceCategory;
  static const char* const kLogPrefix;

  // This value is returned as the tracing id of the child processes by
  // GetTracingProcessId() when tracing is not enabled.
  static const uint64_t kInvalidTracingProcessId;

  static MemoryDumpManager* GetInstance();

  // Invoked once per process to listen to trace begin / end events.
  // Initialization can happen after (Un)RegisterMemoryDumpProvider() calls
  // and the MemoryDumpManager guarantees to support this.
  // On the other side, the MemoryDumpManager will not be fully operational
  // (i.e. will NACK any RequestGlobalMemoryDump()) until initialized.
  // Arguments:
  //  delegate: inversion-of-control interface for embedder-specific behaviors
  //      (multiprocess handshaking). See the lifetime and thread-safety
  //      requirements in the |MemoryDumpManagerDelegate| docstring.
  void Initialize(std::unique_ptr<MemoryDumpManagerDelegate> delegate);

  // (Un)Registers a MemoryDumpProvider instance.
  // Args:
  //  - mdp: the MemoryDumpProvider instance to be registered. MemoryDumpManager
  //      does NOT take memory ownership of |mdp|, which is expected to either
  //      be a singleton or unregister itself.
  //  - name: a friendly name (duplicates allowed). Used for debugging and
  //      run-time profiling of memory-infra internals. Must be a long-lived
  //      C string.
  //  - task_runner: either a SingleThreadTaskRunner or SequencedTaskRunner. All
  //      the calls to |mdp| will be run on the given |task_runner|. If passed
  //      null |mdp| should be able to handle calls on arbitrary threads.
  //  - options: extra optional arguments. See memory_dump_provider.h.
  void RegisterDumpProvider(MemoryDumpProvider* mdp,
                            const char* name,
                            scoped_refptr<SingleThreadTaskRunner> task_runner);
  void RegisterDumpProvider(MemoryDumpProvider* mdp,
                            const char* name,
                            scoped_refptr<SingleThreadTaskRunner> task_runner,
                            MemoryDumpProvider::Options options);
  void RegisterDumpProviderWithSequencedTaskRunner(
      MemoryDumpProvider* mdp,
      const char* name,
      scoped_refptr<SequencedTaskRunner> task_runner,
      MemoryDumpProvider::Options options);
  void UnregisterDumpProvider(MemoryDumpProvider* mdp);

  // Unregisters an unbound dump provider and takes care about its deletion
  // asynchronously. Can be used only for for dump providers with no
  // task-runner affinity.
  // This method takes ownership of the dump provider and guarantees that:
  //  - The |mdp| will be deleted at some point in the near future.
  //  - Its deletion will not happen concurrently with the OnMemoryDump() call.
  // Note that OnMemoryDump() and PollFastMemoryTotal() calls can still happen
  // after this method returns.
  void UnregisterAndDeleteDumpProviderSoon(
      std::unique_ptr<MemoryDumpProvider> mdp);

  // Requests a memory dump. The dump might happen or not depending on the
  // filters and categories specified when enabling tracing.
  // The optional |callback| is executed asynchronously, on an arbitrary thread,
  // to notify about the completion of the global dump (i.e. after all the
  // processes have dumped) and its success (true iff all the dumps were
  // successful).
  void RequestGlobalDump(MemoryDumpType dump_type,
                         MemoryDumpLevelOfDetail level_of_detail,
                         const MemoryDumpCallback& callback);

  // Same as above (still asynchronous), but without callback.
  void RequestGlobalDump(MemoryDumpType dump_type,
                         MemoryDumpLevelOfDetail level_of_detail);

  // TraceLog::EnabledStateObserver implementation.
  void OnTraceLogEnabled() override;
  void OnTraceLogDisabled() override;

  // Enable heap profiling if kEnableHeapProfiling is specified.
  void EnableHeapProfilingIfNeeded();

  // Returns true if the dump mode is allowed for current tracing session.
  bool IsDumpModeAllowed(MemoryDumpLevelOfDetail dump_mode);

  // Lets tests see if a dump provider is registered.
  bool IsDumpProviderRegisteredForTesting(MemoryDumpProvider*);

  // Returns the MemoryDumpSessionState object, which is shared by all the
  // ProcessMemoryDump and MemoryAllocatorDump instances through all the tracing
  // session lifetime.
  const scoped_refptr<MemoryDumpSessionState>& session_state_for_testing()
      const {
    return session_state_;
  }

  // Returns a unique id for identifying the processes. The id can be
  // retrieved by child processes only when tracing is enabled. This is
  // intended to express cross-process sharing of memory dumps on the
  // child-process side, without having to know its own child process id.
  uint64_t GetTracingProcessId() const { return tracing_process_id_; }
  void set_tracing_process_id(uint64_t tracing_process_id) {
    tracing_process_id_ = tracing_process_id;
  }

  // Returns the name for a the allocated_objects dump. Use this to declare
  // suballocator dumps from other dump providers.
  // It will return nullptr if there is no dump provider for the system
  // allocator registered (which is currently the case for Mac OS).
  const char* system_allocator_pool_name() const {
    return kSystemAllocatorPoolName;
  };

  // When set to true, calling |RegisterMemoryDumpProvider| is a no-op.
  void set_dumper_registrations_ignored_for_testing(bool ignored) {
    dumper_registrations_ignored_for_testing_ = ignored;
  }

 private:
  friend std::default_delete<MemoryDumpManager>;  // For the testing instance.
  friend struct DefaultSingletonTraits<MemoryDumpManager>;
  friend class MemoryDumpManagerDelegate;
  friend class MemoryDumpManagerTest;
  friend class MemoryDumpScheduler;
  friend class memory_instrumentation::MemoryDumpManagerDelegateImplTest;

  // Holds the state of a process memory dump that needs to be carried over
  // across task runners in order to fulfil an asynchronous CreateProcessDump()
  // request. At any time exactly one task runner owns a
  // ProcessMemoryDumpAsyncState.
  struct ProcessMemoryDumpAsyncState {
    ProcessMemoryDumpAsyncState(
        MemoryDumpRequestArgs req_args,
        const MemoryDumpProviderInfo::OrderedSet& dump_providers,
        scoped_refptr<MemoryDumpSessionState> session_state,
        MemoryDumpCallback callback,
        scoped_refptr<SingleThreadTaskRunner> dump_thread_task_runner);
    ~ProcessMemoryDumpAsyncState();

    // Gets or creates the memory dump container for the given target process.
    ProcessMemoryDump* GetOrCreateMemoryDumpContainerForProcess(
        ProcessId pid,
        const MemoryDumpArgs& dump_args);

    // A map of ProcessId -> ProcessMemoryDump, one for each target process
    // being dumped from the current process. Typically each process dumps only
    // for itself, unless dump providers specify a different |target_process| in
    // MemoryDumpProvider::Options.
    std::map<ProcessId, std::unique_ptr<ProcessMemoryDump>> process_dumps;

    // The arguments passed to the initial CreateProcessDump() request.
    const MemoryDumpRequestArgs req_args;

    // An ordered sequence of dump providers that have to be invoked to complete
    // the dump. This is a copy of |dump_providers_| at the beginning of a dump
    // and becomes empty at the end, when all dump providers have been invoked.
    std::vector<scoped_refptr<MemoryDumpProviderInfo>> pending_dump_providers;

    // The trace-global session state.
    scoped_refptr<MemoryDumpSessionState> session_state;

    // Callback passed to the initial call to CreateProcessDump().
    MemoryDumpCallback callback;

    // The |success| field that will be passed as argument to the |callback|.
    bool dump_successful;

    // The thread on which FinalizeDumpAndAddToTrace() (and hence |callback|)
    // should be invoked. This is the thread on which the initial
    // CreateProcessDump() request was called.
    const scoped_refptr<SingleThreadTaskRunner> callback_task_runner;

    // The thread on which unbound dump providers should be invoked.
    // This is essentially |dump_thread_|.task_runner() but needs to be kept
    // as a separate variable as it needs to be accessed by arbitrary dumpers'
    // threads outside of the lock_ to avoid races when disabling tracing.
    // It is immutable for all the duration of a tracing session.
    const scoped_refptr<SingleThreadTaskRunner> dump_thread_task_runner;

   private:
    DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDumpAsyncState);
  };

  static const int kMaxConsecutiveFailuresCount;
  static const char* const kSystemAllocatorPoolName;

  MemoryDumpManager();
  ~MemoryDumpManager() override;

  static void SetInstanceForTesting(MemoryDumpManager* instance);
  static uint32_t GetDumpsSumKb(const std::string&, const ProcessMemoryDump*);
  static void FinalizeDumpAndAddToTrace(
      std::unique_ptr<ProcessMemoryDumpAsyncState> pmd_async_state);

  // Internal, used only by MemoryDumpManagerDelegate.
  // Creates a memory dump for the current process and appends it to the trace.
  // |callback| will be invoked asynchronously upon completion on the same
  // thread on which CreateProcessDump() was called.
  void CreateProcessDump(const MemoryDumpRequestArgs& args,
                         const MemoryDumpCallback& callback);

  // Calls InvokeOnMemoryDump() for the next MDP on the task runner specified by
  // the MDP while registration. On failure to do so, skips and continues to
  // next MDP.
  void SetupNextMemoryDump(
      std::unique_ptr<ProcessMemoryDumpAsyncState> pmd_async_state);

  // Invokes OnMemoryDump() of the next MDP and calls SetupNextMemoryDump() at
  // the end to continue the ProcessMemoryDump. Should be called on the MDP task
  // runner.
  void InvokeOnMemoryDump(ProcessMemoryDumpAsyncState* owned_pmd_async_state);

  // Records a quick total memory usage in |memory_total|. This is used to track
  // and detect peaks in the memory usage of the process without having to
  // record all data from dump providers. This value is approximate to trade-off
  // speed, and not consistent with the rest of the memory-infra metrics. Must
  // be called on the dump thread.
  // Returns true if |memory_total| was updated by polling at least 1 MDP.
  bool PollFastMemoryTotal(uint64_t* memory_total);

  // Helper for RegierDumpProvider* functions.
  void RegisterDumpProviderInternal(
      MemoryDumpProvider* mdp,
      const char* name,
      scoped_refptr<SequencedTaskRunner> task_runner,
      const MemoryDumpProvider::Options& options);

  // Helper for the public UnregisterDumpProvider* functions.
  void UnregisterDumpProviderInternal(MemoryDumpProvider* mdp,
                                      bool take_mdp_ownership_and_delete_async);

  // Adds / removes provider that supports polling to
  // |dump_providers_for_polling_|.
  void RegisterPollingMDPOnDumpThread(
      scoped_refptr<MemoryDumpProviderInfo> mdpinfo);
  void UnregisterPollingMDPOnDumpThread(
      scoped_refptr<MemoryDumpProviderInfo> mdpinfo);

  // An ordererd set of registered MemoryDumpProviderInfo(s), sorted by task
  // runner affinity (MDPs belonging to the same task runners are adjacent).
  MemoryDumpProviderInfo::OrderedSet dump_providers_;

  // A copy of mdpinfo list that support polling. It must be accessed only on
  // the dump thread if dump thread exists.
  MemoryDumpProviderInfo::OrderedSet dump_providers_for_polling_;

  // Shared among all the PMDs to keep state scoped to the tracing session.
  scoped_refptr<MemoryDumpSessionState> session_state_;

  // The list of names of dump providers that are blacklisted from strict thread
  // affinity check on unregistration.
  std::unordered_set<StringPiece, StringPieceHash>
      strict_thread_check_blacklist_;

  std::unique_ptr<MemoryDumpManagerDelegate> delegate_;

  // Protects from concurrent accesses to the |dump_providers_*| and |delegate_|
  // to guard against disabling logging while dumping on another thread.
  Lock lock_;

  // Optimization to avoid attempting any memory dump (i.e. to not walk an empty
  // dump_providers_enabled_ list) when tracing is not enabled.
  subtle::AtomicWord memory_tracing_enabled_;

  // Thread used for MemoryDumpProviders which don't specify a task runner
  // affinity.
  std::unique_ptr<Thread> dump_thread_;

  // The unique id of the child process. This is created only for tracing and is
  // expected to be valid only when tracing is enabled.
  uint64_t tracing_process_id_;

  // When true, calling |RegisterMemoryDumpProvider| is a no-op.
  bool dumper_registrations_ignored_for_testing_;

  // Whether new memory dump providers should be told to enable heap profiling.
  bool heap_profiling_enabled_;

  DISALLOW_COPY_AND_ASSIGN(MemoryDumpManager);
};

// The delegate is supposed to be long lived (read: a Singleton) and thread
// safe (i.e. should expect calls from any thread and handle thread hopping).
class BASE_EXPORT MemoryDumpManagerDelegate {
 public:
  MemoryDumpManagerDelegate() {}
  virtual ~MemoryDumpManagerDelegate() {}

  virtual void RequestGlobalMemoryDump(const MemoryDumpRequestArgs& args,
                                       const MemoryDumpCallback& callback) = 0;

  virtual bool IsCoordinator() const = 0;

 protected:
  void CreateProcessDump(const MemoryDumpRequestArgs& args,
                         const MemoryDumpCallback& callback) {
    MemoryDumpManager::GetInstance()->CreateProcessDump(args, callback);
  }

 private:
  DISALLOW_COPY_AND_ASSIGN(MemoryDumpManagerDelegate);
};

}  // namespace trace_event
}  // namespace base

#endif  // BASE_TRACE_EVENT_MEMORY_DUMP_MANAGER_H_