chromium/src/heap-profile-table.h

// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2006, Google Inc.
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// ---
// Author: Sanjay Ghemawat
//         Maxim Lifantsev (refactoring)
//

#ifndef BASE_HEAP_PROFILE_TABLE_H_
#define BASE_HEAP_PROFILE_TABLE_H_

#include "addressmap-inl.h"
#include "base/basictypes.h"
#include "base/logging.h"   // for RawFD
#include "heap-profile-stats.h"

// Table to maintain a heap profile data inside,
// i.e. the set of currently active heap memory allocations.
// thread-unsafe and non-reentrant code:
// each instance object must be used by one thread
// at a time w/o self-recursion.
//
// TODO(maxim): add a unittest for this class.
class HeapProfileTable {
 public:

  // Extension to be used for heap pforile files.
  static const char kFileExt[];

  // Longest stack trace we record.
  static const int kMaxStackDepth = 32;

  // data types ----------------------------

  // Profile stats.
  typedef HeapProfileStats Stats;

  // Info we can return about an allocation.
  struct AllocInfo {
    size_t object_size;  // size of the allocation
    const void* const* call_stack;  // call stack that made the allocation call
    int stack_depth;  // depth of call_stack
    bool live;
    bool ignored;
  };

  // Info we return about an allocation context.
  // An allocation context is a unique caller stack trace
  // of an allocation operation.
  struct AllocContextInfo : public Stats {
    int stack_depth;                // Depth of stack trace
    const void* const* call_stack;  // Stack trace
  };

  // Memory (de)allocator interface we'll use.
  typedef void* (*Allocator)(size_t size);
  typedef void  (*DeAllocator)(void* ptr);

  // interface ---------------------------

  HeapProfileTable(Allocator alloc, DeAllocator dealloc, bool profile_mmap);
  ~HeapProfileTable();

  // Collect the stack trace for the function that asked to do the
  // allocation for passing to RecordAlloc() below.
  //
  // The stack trace is stored in 'stack'. The stack depth is returned.
  //
  // 'skip_count' gives the number of stack frames between this call
  // and the memory allocation function.
  static int GetCallerStackTrace(int skip_count, void* stack[kMaxStackDepth]);

  // Record an allocation at 'ptr' of 'bytes' bytes.  'stack_depth'
  // and 'call_stack' identifying the function that requested the
  // allocation. They can be generated using GetCallerStackTrace() above.
  void RecordAlloc(const void* ptr, size_t bytes,
                   int stack_depth, const void* const call_stack[]);

  // Record the deallocation of memory at 'ptr'.
  void RecordFree(const void* ptr);

  // Return true iff we have recorded an allocation at 'ptr'.
  // If yes, fill *object_size with the allocation byte size.
  bool FindAlloc(const void* ptr, size_t* object_size) const;
  // Same as FindAlloc, but fills all of *info.
  bool FindAllocDetails(const void* ptr, AllocInfo* info) const;

  // Return true iff "ptr" points into a recorded allocation
  // If yes, fill *object_ptr with the actual allocation address
  // and *object_size with the allocation byte size.
  // max_size specifies largest currently possible allocation size.
  bool FindInsideAlloc(const void* ptr, size_t max_size,
                       const void** object_ptr, size_t* object_size) const;

  // If "ptr" points to a recorded allocation and it's not marked as live
  // mark it as live and return true. Else return false.
  // All allocations start as non-live.
  bool MarkAsLive(const void* ptr);

  // If "ptr" points to a recorded allocation, mark it as "ignored".
  // Ignored objects are treated like other objects, except that they
  // are skipped in heap checking reports.
  void MarkAsIgnored(const void* ptr);

  // Return current total (de)allocation statistics.  It doesn't contain
  // mmap'ed regions.
  const Stats& total() const { return total_; }

  // Allocation data iteration callback: gets passed object pointer and
  // fully-filled AllocInfo.
  typedef void (*AllocIterator)(const void* ptr, const AllocInfo& info);

  // Iterate over the allocation profile data calling "callback"
  // for every allocation.
  void IterateAllocs(AllocIterator callback) const {
    address_map_->Iterate(MapArgsAllocIterator, callback);
  }

  // Allocation context profile data iteration callback
  typedef void (*AllocContextIterator)(const AllocContextInfo& info);

  // Iterate over the allocation context profile data calling "callback"
  // for every allocation context. Allocation contexts are ordered by the
  // size of allocated space.
  void IterateOrderedAllocContexts(AllocContextIterator callback) const;

  // Fill profile data into buffer 'buf' of size 'size'
  // and return the actual size occupied by the dump in 'buf'.
  // The profile buckets are dumped in the decreasing order
  // of currently allocated bytes.
  // We do not provision for 0-terminating 'buf'.
  int FillOrderedProfile(char buf[], int size) const;

  // Cleanup any old profile files matching prefix + ".*" + kFileExt.
  static void CleanupOldProfiles(const char* prefix);

  // Return a snapshot of the current contents of *this.
  // Caller must call ReleaseSnapshot() on result when no longer needed.
  // The result is only valid while this exists and until
  // the snapshot is discarded by calling ReleaseSnapshot().
  class Snapshot;
  Snapshot* TakeSnapshot();

  // Release a previously taken snapshot.  snapshot must not
  // be used after this call.
  void ReleaseSnapshot(Snapshot* snapshot);

  // Return a snapshot of every non-live, non-ignored object in *this.
  // If "base" is non-NULL, skip any objects present in "base".
  // As a side-effect, clears the "live" bit on every live object in *this.
  // Caller must call ReleaseSnapshot() on result when no longer needed.
  Snapshot* NonLiveSnapshot(Snapshot* base);

 private:

  // data types ----------------------------

  // Hash table bucket to hold (de)allocation stats
  // for a given allocation call stack trace.
  typedef HeapProfileBucket Bucket;

  // Info stored in the address map
  struct AllocValue {
    // Access to the stack-trace bucket
    Bucket* bucket() const {
      return reinterpret_cast<Bucket*>(bucket_rep & ~uintptr_t(kMask));
    }
    // This also does set_live(false).
    void set_bucket(Bucket* b) { bucket_rep = reinterpret_cast<uintptr_t>(b); }
    size_t  bytes;   // Number of bytes in this allocation

    // Access to the allocation liveness flag (for leak checking)
    bool live() const { return bucket_rep & kLive; }
    void set_live(bool l) {
      bucket_rep = (bucket_rep & ~uintptr_t(kLive)) | (l ? kLive : 0);
    }

    // Should this allocation be ignored if it looks like a leak?
    bool ignore() const { return bucket_rep & kIgnore; }
    void set_ignore(bool r) {
      bucket_rep = (bucket_rep & ~uintptr_t(kIgnore)) | (r ? kIgnore : 0);
    }

   private:
    // We store a few bits in the bottom bits of bucket_rep.
    // (Alignment is at least four, so we have at least two bits.)
    static const int kLive = 1;
    static const int kIgnore = 2;
    static const int kMask = kLive | kIgnore;

    uintptr_t bucket_rep;
  };

  // helper for FindInsideAlloc
  static size_t AllocValueSize(const AllocValue& v) { return v.bytes; }

  typedef AddressMap<AllocValue> AllocationMap;

  // Arguments that need to be passed DumpBucketIterator callback below.
  struct BufferArgs {
    BufferArgs(char* buf_arg, int buflen_arg, int bufsize_arg)
        : buf(buf_arg),
          buflen(buflen_arg),
          bufsize(bufsize_arg) {
    }

    char* buf;
    int buflen;
    int bufsize;

    DISALLOW_COPY_AND_ASSIGN(BufferArgs);
  };

  // Arguments that need to be passed DumpNonLiveIterator callback below.
  struct DumpArgs {
    DumpArgs(RawFD fd_arg, Stats* profile_stats_arg)
        : fd(fd_arg),
          profile_stats(profile_stats_arg) {
    }

    RawFD fd;  // file to write to
    Stats* profile_stats;  // stats to update (may be NULL)
  };

  // helpers ----------------------------

  // Unparse bucket b and print its portion of profile dump into buf.
  // We return the amount of space in buf that we use.  We start printing
  // at buf + buflen, and promise not to go beyond buf + bufsize.
  // We do not provision for 0-terminating 'buf'.
  //
  // If profile_stats is non-NULL, we update *profile_stats by
  // counting bucket b.
  //
  // "extra" is appended to the unparsed bucket.  Typically it is empty,
  // but may be set to something like " heapprofile" for the total
  // bucket to indicate the type of the profile.
  static int UnparseBucket(const Bucket& b,
                           char* buf, int buflen, int bufsize,
                           const char* extra,
                           Stats* profile_stats);

  // Get the bucket for the caller stack trace 'key' of depth 'depth'
  // creating the bucket if needed.
  Bucket* GetBucket(int depth, const void* const key[]);

  // Helper for IterateAllocs to do callback signature conversion
  // from AllocationMap::Iterate to AllocIterator.
  static void MapArgsAllocIterator(const void* ptr, AllocValue* v,
                                   AllocIterator callback) {
    AllocInfo info;
    info.object_size = v->bytes;
    info.call_stack = v->bucket()->stack;
    info.stack_depth = v->bucket()->depth;
    info.live = v->live();
    info.ignored = v->ignore();
    callback(ptr, info);
  }

  // Helper to dump a bucket.
  inline static void DumpBucketIterator(const Bucket* bucket,
                                        BufferArgs* args);

  // Helper for DumpNonLiveProfile to do object-granularity
  // heap profile dumping. It gets passed to AllocationMap::Iterate.
  inline static void DumpNonLiveIterator(const void* ptr, AllocValue* v,
                                         const DumpArgs& args);

  // Helper for IterateOrderedAllocContexts and FillOrderedProfile.
  // Creates a sorted list of Buckets whose length is num_buckets_.
  // The caller is responsible for deallocating the returned list.
  Bucket** MakeSortedBucketList() const;

  // Helper for TakeSnapshot.  Saves object to snapshot.
  static void AddToSnapshot(const void* ptr, AllocValue* v, Snapshot* s);

  // Arguments passed to AddIfNonLive
  struct AddNonLiveArgs {
    Snapshot* dest;
    Snapshot* base;
  };

  // Helper for NonLiveSnapshot.  Adds the object to the destination
  // snapshot if it is non-live.
  static void AddIfNonLive(const void* ptr, AllocValue* v,
                           AddNonLiveArgs* arg);

  // Write contents of "*allocations" as a heap profile to
  // "file_name".  "total" must contain the total of all entries in
  // "*allocations".
  static bool WriteProfile(const char* file_name,
                           const Bucket& total,
                           AllocationMap* allocations);

  // data ----------------------------

  // Memory (de)allocator that we use.
  Allocator alloc_;
  DeAllocator dealloc_;

  // Overall profile stats; we use only the Stats part,
  // but make it a Bucket to pass to UnparseBucket.
  Bucket total_;

  bool profile_mmap_;

  // Bucket hash table for malloc.
  // We hand-craft one instead of using one of the pre-written
  // ones because we do not want to use malloc when operating on the table.
  // It is only few lines of code, so no big deal.
  Bucket** bucket_table_;
  int num_buckets_;

  // Map of all currently allocated objects and mapped regions we know about.
  AllocationMap* address_map_;

  DISALLOW_COPY_AND_ASSIGN(HeapProfileTable);
};

class HeapProfileTable::Snapshot {
 public:
  const Stats& total() const { return total_; }

  // Report anything in this snapshot as a leak.
  // May use new/delete for temporary storage.
  // If should_symbolize is true, will fork (which is not threadsafe)
  // to turn addresses into symbol names.  Set to false for maximum safety.
  // Also writes a heap profile to "filename" that contains
  // all of the objects in this snapshot.
  void ReportLeaks(const char* checker_name, const char* filename,
                   bool should_symbolize);

  // Report the addresses of all leaked objects.
  // May use new/delete for temporary storage.
  void ReportIndividualObjects();

  bool Empty() const {
    return (total_.allocs == 0) && (total_.alloc_size == 0);
  }

 private:
  friend class HeapProfileTable;

  // Total count/size are stored in a Bucket so we can reuse UnparseBucket
  Bucket total_;

  // We share the Buckets managed by the parent table, but have our
  // own object->bucket map.
  AllocationMap map_;

  Snapshot(Allocator alloc, DeAllocator dealloc) : map_(alloc, dealloc) {
    memset(&total_, 0, sizeof(total_));
  }

  // Callback used to populate a Snapshot object with entries found
  // in another allocation map.
  inline void Add(const void* ptr, const AllocValue& v) {
    map_.Insert(ptr, v);
    total_.allocs++;
    total_.alloc_size += v.bytes;
  }

  // Helpers for sorting and generating leak reports
  struct Entry;
  struct ReportState;
  static void ReportCallback(const void* ptr, AllocValue* v, ReportState*);
  static void ReportObject(const void* ptr, AllocValue* v, char*);

  DISALLOW_COPY_AND_ASSIGN(Snapshot);
};

#endif  // BASE_HEAP_PROFILE_TABLE_H_