// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// ---
// Author: Sanjay Ghemawat
//
// TODO: Log large allocations

#include <assert.h>
#include <config.h>
#include <errno.h>
#include <inttypes.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <time.h>

#ifdef HAVE_FCNTL_H
#include <fcntl.h>    // for open()
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <gperftools/heap-profiler.h>

#include "base/logging.h"
#include "base/googleinit.h"
#include "base/commandlineflags.h"
#include "tcmalloc_guard.h"
#include <gperftools/malloc_hook.h>
#include <gperftools/malloc_extension.h>
#include "base/spinlock.h"
#include "base/low_level_alloc.h"
#include "base/sysinfo.h"      // for GetUniquePathFromEnv()
#include "heap-profile-table.h"
#include "malloc_backtrace.h"

#ifndef	PATH_MAX
#ifdef MAXPATHLEN
#define	PATH_MAX	MAXPATHLEN
#else
#define	PATH_MAX	4096         // seems conservative for max filename len!
#endif
#endif

using tcmalloc::LowLevelAlloc;

//----------------------------------------------------------------------
// Flags that control heap-profiling
//
// The thread-safety of the profiler depends on these being immutable
// after main starts, so don't change them.
//----------------------------------------------------------------------

DEFINE_int64(heap_profile_allocation_interval,
             EnvToInt64("HEAP_PROFILE_ALLOCATION_INTERVAL", 1 << 30 /*1GB*/),
             "If non-zero, dump heap profiling information once every "
             "specified number of bytes allocated by the program since "
             "the last dump.");
DEFINE_int64(heap_profile_deallocation_interval,
             EnvToInt64("HEAP_PROFILE_DEALLOCATION_INTERVAL", 0),
             "If non-zero, dump heap profiling information once every "
             "specified number of bytes deallocated by the program "
             "since the last dump.");
// We could also add flags that report whenever inuse_bytes changes by
// X or -X, but there hasn't been a need for that yet, so we haven't.
DEFINE_int64(heap_profile_inuse_interval,
             EnvToInt64("HEAP_PROFILE_INUSE_INTERVAL", 100 << 20 /*100MB*/),
             "If non-zero, dump heap profiling information whenever "
             "the high-water memory usage mark increases by the specified "
             "number of bytes.");
DEFINE_int64(heap_profile_time_interval,
             EnvToInt64("HEAP_PROFILE_TIME_INTERVAL", 0),
             "If non-zero, dump heap profiling information once every "
             "specified number of seconds since the last dump.");


//----------------------------------------------------------------------
// Locking
//----------------------------------------------------------------------

// A pthread_mutex has way too much lock contention to be used here.
//
// I would like to use Mutex, but it can call malloc(),
// which can cause us to fall into an infinite recursion.
//
// So we use a simple spinlock.
static SpinLock heap_lock;

//----------------------------------------------------------------------
// Simple allocator for heap profiler's internal memory
//----------------------------------------------------------------------

static LowLevelAlloc::Arena *heap_profiler_memory;

static void* ProfilerMalloc(size_t bytes) {
  return LowLevelAlloc::AllocWithArena(bytes, heap_profiler_memory);
}
static void ProfilerFree(void* p) {
  LowLevelAlloc::Free(p);
}

// We use buffers of this size in DoGetHeapProfile.


//----------------------------------------------------------------------
// Profiling control/state data
//----------------------------------------------------------------------

// Access to all of these is protected by heap_lock.
static bool  is_on;           // If are on as a subsytem.
static bool  dumping;         // Dumping status to prevent recursion
static char* filename_prefix; // Prefix used for profile file names
                              // (nullptr if no need for dumping yet)
static int   dump_count;      // How many dumps so far
static int64_t last_dump_alloc;  // alloc_size when did we last dump
static int64_t last_dump_free;   // free_size when did we last dump
static int64_t high_water_mark;  // In-use-bytes at last high-water dump
static int64_t last_dump_time;   // The time of the last dump

static HeapProfileTable* heap_profile;  // the heap profile table

//----------------------------------------------------------------------
// Profile generation
//----------------------------------------------------------------------

// Input must be a buffer of size at least 1MB.
static void DoDumpHeapProfileLocked(tcmalloc::GenericWriter* writer) {
  RAW_DCHECK(heap_lock.IsHeld(), "");
  if (is_on) {
    heap_profile->SaveProfile(writer);
  }
}

extern "C" char* GetHeapProfile() {
  tcmalloc::ChunkedWriterConfig config(ProfilerMalloc, ProfilerFree);

  return tcmalloc::WithWriterToStrDup(config, [] (tcmalloc::GenericWriter* writer) {
    SpinLockHolder l(&heap_lock);
    DoDumpHeapProfileLocked(writer);
  });
}

// defined below
static void NewHook(const void* ptr, size_t size);
static void DeleteHook(const void* ptr);

// Helper for HeapProfilerDump.
static void DumpProfileLocked(const char* reason) {
  RAW_DCHECK(heap_lock.IsHeld(), "");
  RAW_DCHECK(is_on, "");
  RAW_DCHECK(!dumping, "");

  if (filename_prefix == nullptr) return;  // we do not yet need dumping

  dumping = true;

  // Make file name
  char file_name[1000];
  dump_count++;
  snprintf(file_name, sizeof(file_name), "%s.%04d%s",
           filename_prefix, dump_count, HeapProfileTable::kFileExt);

  // Dump the profile
  RAW_VLOG(0, "Dumping heap profile to %s (%s)", file_name, reason);
  // We must use file routines that don't access memory, since we hold
  // a memory lock now.
  RawFD fd = RawOpenForWriting(file_name);
  if (fd == kIllegalRawFD) {
    RAW_LOG(ERROR, "Failed dumping heap profile to %s. Numeric errno is %d", file_name, errno);
    dumping = false;
    return;
  }

  using FileWriter = tcmalloc::RawFDGenericWriter<1 << 20>;
  FileWriter* writer = new (ProfilerMalloc(sizeof(FileWriter))) FileWriter(fd);

  DoDumpHeapProfileLocked(writer);

  // Note: as part of running destructor, it saves whatever stuff we left buffered in the writer
  writer->~FileWriter();
  ProfilerFree(writer);

  RawClose(fd);

  dumping = false;
}

//----------------------------------------------------------------------
// Profile collection
//----------------------------------------------------------------------

// Dump a profile after either an allocation or deallocation, if
// the memory use has changed enough since the last dump.
static void MaybeDumpProfileLocked() {
  if (!dumping) {
    const HeapProfileTable::Stats& total = heap_profile->total();
    const int64_t inuse_bytes = total.alloc_size - total.free_size;
    bool need_to_dump = false;
    char buf[128];

    if (FLAGS_heap_profile_allocation_interval > 0 &&
        total.alloc_size >=
        last_dump_alloc + FLAGS_heap_profile_allocation_interval) {
      snprintf(buf, sizeof(buf), ("%" PRId64 " MB allocated cumulatively, "
                                  "%" PRId64 " MB currently in use"),
               total.alloc_size >> 20, inuse_bytes >> 20);
      need_to_dump = true;
    } else if (FLAGS_heap_profile_deallocation_interval > 0 &&
               total.free_size >=
               last_dump_free + FLAGS_heap_profile_deallocation_interval) {
      snprintf(buf, sizeof(buf), ("%" PRId64 " MB freed cumulatively, "
                                  "%" PRId64 " MB currently in use"),
               total.free_size >> 20, inuse_bytes >> 20);
      need_to_dump = true;
    } else if (FLAGS_heap_profile_inuse_interval > 0 &&
               inuse_bytes >
               high_water_mark + FLAGS_heap_profile_inuse_interval) {
      snprintf(buf, sizeof(buf), "%" PRId64 " MB currently in use",
               inuse_bytes >> 20);
      need_to_dump = true;
    } else if (FLAGS_heap_profile_time_interval > 0 ) {
      int64_t current_time = time(nullptr);
      if (current_time - last_dump_time >=
          FLAGS_heap_profile_time_interval) {
        snprintf(buf, sizeof(buf), "%" PRId64 " sec since the last dump",
                 current_time - last_dump_time);
        need_to_dump = true;
        last_dump_time = current_time;
      }
    }
    if (need_to_dump) {
      DumpProfileLocked(buf);

      last_dump_alloc = total.alloc_size;
      last_dump_free = total.free_size;
      if (inuse_bytes > high_water_mark)
        high_water_mark = inuse_bytes;
    }
  }
}

//----------------------------------------------------------------------
// Allocation/deallocation hooks for MallocHook
//----------------------------------------------------------------------

// Record an allocation in the profile.
static void NewHook(const void* ptr, size_t bytes) {
  if (!ptr) return;

  // Take the stack trace outside the critical section.
  static constexpr int kDepth = 32;
  void* stack[kDepth];
  int depth = tcmalloc::GrabBacktrace(stack, kDepth, 1);
  SpinLockHolder l(&heap_lock);
  if (is_on) {
    heap_profile->RecordAlloc(ptr, bytes, depth, stack);
    MaybeDumpProfileLocked();
  }
}

// Record a deallocation in the profile.
static void DeleteHook(const void* ptr) {
  if (!ptr) return;

  SpinLockHolder l(&heap_lock);
  if (is_on) {
    heap_profile->RecordFree(ptr);
    MaybeDumpProfileLocked();
  }
}

//----------------------------------------------------------------------
// Starting/stopping/dumping
//----------------------------------------------------------------------

extern "C" void HeapProfilerStart(const char* prefix) {
  // A bit of a kludge. When we dump heap profiles on certain systems
  // (e.g. FreeBSD), we'll invoke GetProgramInvocationName and it'll
  // malloc. And we cannot malloc when under heap profiler lock(s). So
  // lets do it now (it caches the name internally).
  (void)tcmalloc::GetProgramInvocationName();

  SpinLockHolder l(&heap_lock);

  if (is_on) return;

  is_on = true;

  RAW_VLOG(0, "Starting tracking the heap");

  // This should be done before the hooks are set up, since it should
  // call new, and we want that to be accounted for correctly.
  MallocExtension::Initialize();

  heap_profiler_memory = LowLevelAlloc::NewArena();

  heap_profile = new(ProfilerMalloc(sizeof(HeapProfileTable)))
      HeapProfileTable(ProfilerMalloc, ProfilerFree);

  last_dump_alloc = 0;
  last_dump_free = 0;
  high_water_mark = 0;
  last_dump_time = 0;

  // We do not reset dump_count so if the user does a sequence of
  // HeapProfilerStart/HeapProfileStop, we will get a continuous
  // sequence of profiles.

  // Now set the hooks that capture new/delete and malloc/free.
  RAW_CHECK(MallocHook::AddNewHook(&NewHook), "");
  RAW_CHECK(MallocHook::AddDeleteHook(&DeleteHook), "");

  // Copy filename prefix
  RAW_DCHECK(filename_prefix == nullptr, "");
  const int prefix_length = strlen(prefix);
  filename_prefix = reinterpret_cast<char*>(ProfilerMalloc(prefix_length + 1));
  memcpy(filename_prefix, prefix, prefix_length);
  filename_prefix[prefix_length] = '\0';
}

extern "C" int IsHeapProfilerRunning() {
  SpinLockHolder l(&heap_lock);
  return is_on ? 1 : 0;   // return an int, because C code doesn't have bool
}

extern "C" void HeapProfilerStop() {
  SpinLockHolder l(&heap_lock);

  if (!is_on) return;

  // Unset our new/delete hooks, checking they were set:
  RAW_CHECK(MallocHook::RemoveNewHook(&NewHook), "");
  RAW_CHECK(MallocHook::RemoveDeleteHook(&DeleteHook), "");

  // free profile
  heap_profile->~HeapProfileTable();
  ProfilerFree(heap_profile);
  heap_profile = nullptr;

  // free prefix
  ProfilerFree(filename_prefix);
  filename_prefix = nullptr;

  if (!LowLevelAlloc::DeleteArena(heap_profiler_memory)) {
    RAW_LOG(FATAL, "Memory leak in HeapProfiler:");
  }

  is_on = false;
}

extern "C" void HeapProfilerDump(const char *reason) {
  SpinLockHolder l(&heap_lock);
  if (is_on && !dumping) {
    DumpProfileLocked(reason);
  }
}

// Signal handler that is registered when a user selectable signal
// number is defined in the environment variable HEAPPROFILESIGNAL.
static void HeapProfilerDumpSignal(int signal_number) {
  (void)signal_number;
  if (!heap_lock.TryLock()) {
    return;
  }
  if (is_on && !dumping) {
    DumpProfileLocked("signal");
  }
  heap_lock.Unlock();
}


//----------------------------------------------------------------------
// Initialization/finalization code
//----------------------------------------------------------------------

// Initialization code
static void HeapProfilerInit() {
  // Everything after this point is for setting up the profiler based on envvar
  char fname[PATH_MAX];
  if (!GetUniquePathFromEnv("HEAPPROFILE", fname)) {
    return;
  }
  // We do a uid check so we don't write out files in a setuid executable.
#ifdef HAVE_GETEUID
  if (getuid() != geteuid()) {
    RAW_LOG(WARNING, ("HeapProfiler: ignoring HEAPPROFILE because "
                      "program seems to be setuid\n"));
    return;
  }
#endif

  char *signal_number_str = getenv("HEAPPROFILESIGNAL");
  if (signal_number_str != nullptr) {
    long int signal_number = strtol(signal_number_str, nullptr, 10);
    intptr_t old_signal_handler = reinterpret_cast<intptr_t>(signal(signal_number, HeapProfilerDumpSignal));
    if (old_signal_handler == reinterpret_cast<intptr_t>(SIG_ERR)) {
      RAW_LOG(FATAL, "Failed to set signal. Perhaps signal number %s is invalid\n", signal_number_str);
    } else if (old_signal_handler == 0) {
      RAW_LOG(INFO,"Using signal %d as heap profiling switch", signal_number);
    } else {
      RAW_LOG(FATAL, "Signal %d already in use\n", signal_number);
    }
  }

  HeapProfileTable::CleanupOldProfiles(fname);

  HeapProfilerStart(fname);
}

// class used for finalization -- dumps the heap-profile at program exit
struct HeapProfileEndWriter {
  ~HeapProfileEndWriter() {
    char buf[128];
    if (heap_profile) {
      const HeapProfileTable::Stats& total = heap_profile->total();
      const int64_t inuse_bytes = total.alloc_size - total.free_size;

      if ((inuse_bytes >> 20) > 0) {
        snprintf(buf, sizeof(buf), ("Exiting, %" PRId64 " MB in use"),
                 inuse_bytes >> 20);
      } else if ((inuse_bytes >> 10) > 0) {
        snprintf(buf, sizeof(buf), ("Exiting, %" PRId64 " kB in use"),
                 inuse_bytes >> 10);
      } else {
        snprintf(buf, sizeof(buf), ("Exiting, %" PRId64 " bytes in use"),
                 inuse_bytes);
      }
    } else {
      snprintf(buf, sizeof(buf), ("Exiting"));
    }
    HeapProfilerDump(buf);
  }
};

// We want to make sure tcmalloc is up and running before starting the profiler
static const TCMallocGuard tcmalloc_initializer;
REGISTER_MODULE_INITIALIZER(heapprofiler, HeapProfilerInit());
static HeapProfileEndWriter heap_profile_end_writer;
