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Unified Diff: base/trace_event/heap_profiler_heap_dump_writer.cc

Issue 2650863003: [tracing] Switch to new heap dump format. (Closed)
Patch Set: Rebase Created 3 years, 6 months ago
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Index: base/trace_event/heap_profiler_heap_dump_writer.cc
diff --git a/base/trace_event/heap_profiler_heap_dump_writer.cc b/base/trace_event/heap_profiler_heap_dump_writer.cc
deleted file mode 100644
index f06f64cde5174ce74251e084ce402f49bb97c070..0000000000000000000000000000000000000000
--- a/base/trace_event/heap_profiler_heap_dump_writer.cc
+++ /dev/null
@@ -1,324 +0,0 @@
-// 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.
-
-#include "base/trace_event/heap_profiler_heap_dump_writer.h"
-
-#include <stdint.h>
-
-#include <algorithm>
-#include <iterator>
-#include <tuple>
-#include <utility>
-#include <vector>
-
-#include "base/format_macros.h"
-#include "base/logging.h"
-#include "base/macros.h"
-#include "base/strings/stringprintf.h"
-#include "base/trace_event/heap_profiler_serialization_state.h"
-#include "base/trace_event/heap_profiler_stack_frame_deduplicator.h"
-#include "base/trace_event/heap_profiler_type_name_deduplicator.h"
-#include "base/trace_event/trace_config.h"
-#include "base/trace_event/trace_event_argument.h"
-#include "base/trace_event/trace_log.h"
-
-// Most of what the |HeapDumpWriter| does is aggregating detailed information
-// about the heap and deciding what to dump. The Input to this process is a list
-// of |AllocationContext|s and size pairs.
-//
-// The pairs are grouped into |Bucket|s. A bucket is a group of (context, size)
-// pairs where the properties of the contexts share a prefix. (Type name is
-// considered a list of length one here.) First all pairs are put into one
-// bucket that represents the entire heap. Then this bucket is recursively
-// broken down into smaller buckets. Each bucket keeps track of whether further
-// breakdown is possible.
-
-namespace base {
-namespace trace_event {
-namespace internal {
-namespace {
-
-// Denotes a property of |AllocationContext| to break down by.
-enum class BreakDownMode { kByBacktrace, kByTypeName };
-
-// A group of bytes for which the context shares a prefix.
-struct Bucket {
- Bucket()
- : size(0),
- count(0),
- backtrace_cursor(0),
- is_broken_down_by_type_name(false) {}
-
- std::vector<std::pair<const AllocationContext*, AllocationMetrics>>
- metrics_by_context;
-
- // The sum of the sizes of |metrics_by_context|.
- size_t size;
-
- // The sum of number of allocations of |metrics_by_context|.
- size_t count;
-
- // The index of the stack frame that has not yet been broken down by. For all
- // elements in this bucket, the stack frames 0 up to (but not including) the
- // cursor, must be equal.
- size_t backtrace_cursor;
-
- // When true, the type name for all elements in this bucket must be equal.
- bool is_broken_down_by_type_name;
-};
-
-// Comparison operator to order buckets by their size.
-bool operator<(const Bucket& lhs, const Bucket& rhs) {
- return lhs.size < rhs.size;
-}
-
-// Groups the allocations in the bucket by |break_by|. The buckets in the
-// returned list will have |backtrace_cursor| advanced or
-// |is_broken_down_by_type_name| set depending on the property to group by.
-std::vector<Bucket> GetSubbuckets(const Bucket& bucket,
- BreakDownMode break_by) {
- std::unordered_map<const void*, Bucket> breakdown;
-
- if (break_by == BreakDownMode::kByBacktrace) {
- for (const auto& context_and_metrics : bucket.metrics_by_context) {
- const Backtrace& backtrace = context_and_metrics.first->backtrace;
- const StackFrame* begin = std::begin(backtrace.frames);
- const StackFrame* end = begin + backtrace.frame_count;
- const StackFrame* cursor = begin + bucket.backtrace_cursor;
-
- DCHECK_LE(cursor, end);
-
- if (cursor != end) {
- Bucket& subbucket = breakdown[cursor->value];
- subbucket.size += context_and_metrics.second.size;
- subbucket.count += context_and_metrics.second.count;
- subbucket.metrics_by_context.push_back(context_and_metrics);
- subbucket.backtrace_cursor = bucket.backtrace_cursor + 1;
- subbucket.is_broken_down_by_type_name =
- bucket.is_broken_down_by_type_name;
- DCHECK_GT(subbucket.size, 0u);
- DCHECK_GT(subbucket.count, 0u);
- }
- }
- } else if (break_by == BreakDownMode::kByTypeName) {
- if (!bucket.is_broken_down_by_type_name) {
- for (const auto& context_and_metrics : bucket.metrics_by_context) {
- const AllocationContext* context = context_and_metrics.first;
- Bucket& subbucket = breakdown[context->type_name];
- subbucket.size += context_and_metrics.second.size;
- subbucket.count += context_and_metrics.second.count;
- subbucket.metrics_by_context.push_back(context_and_metrics);
- subbucket.backtrace_cursor = bucket.backtrace_cursor;
- subbucket.is_broken_down_by_type_name = true;
- DCHECK_GT(subbucket.size, 0u);
- DCHECK_GT(subbucket.count, 0u);
- }
- }
- }
-
- std::vector<Bucket> buckets;
- buckets.reserve(breakdown.size());
- for (auto key_bucket : breakdown)
- buckets.push_back(key_bucket.second);
-
- return buckets;
-}
-
-// Breaks down the bucket by |break_by|. Returns only buckets that contribute
-// more than |min_size_bytes| to the total size. The long tail is omitted.
-std::vector<Bucket> BreakDownBy(const Bucket& bucket,
- BreakDownMode break_by,
- size_t min_size_bytes) {
- std::vector<Bucket> buckets = GetSubbuckets(bucket, break_by);
-
- // Ensure that |buckets| is a max-heap (the data structure, not memory heap),
- // so its front contains the largest bucket. Buckets should be iterated
- // ordered by size, but sorting the vector is overkill because the long tail
- // of small buckets will be discarded. By using a max-heap, the optimal case
- // where all but the first bucket are discarded is O(n). The worst case where
- // no bucket is discarded is doing a heap sort, which is O(n log n).
- std::make_heap(buckets.begin(), buckets.end());
-
- // Keep including buckets until adding one would increase the number of
- // bytes accounted for by |min_size_bytes|. The large buckets end up in
- // [it, end()), [begin(), it) is the part that contains the max-heap
- // of small buckets.
- std::vector<Bucket>::iterator it;
- for (it = buckets.end(); it != buckets.begin(); --it) {
- if (buckets.front().size < min_size_bytes)
- break;
-
- // Put the largest bucket in [begin, it) at |it - 1| and max-heapify
- // [begin, it - 1). This puts the next largest bucket at |buckets.front()|.
- std::pop_heap(buckets.begin(), it);
- }
-
- // At this point, |buckets| looks like this (numbers are bucket sizes):
- //
- // <-- max-heap of small buckets --->
- // <-- large buckets by ascending size -->
- // [ 19 | 11 | 13 | 7 | 2 | 5 | ... | 83 | 89 | 97 ]
- // ^ ^ ^
- // | | |
- // begin() it end()
-
- // Discard the long tail of buckets that contribute less than a percent.
- buckets.erase(buckets.begin(), it);
-
- return buckets;
-}
-
-} // namespace
-
-bool operator<(Entry lhs, Entry rhs) {
- // There is no need to compare |size|. If the backtrace and type name are
- // equal then the sizes must be equal as well.
- return std::tie(lhs.stack_frame_id, lhs.type_id) <
- std::tie(rhs.stack_frame_id, rhs.type_id);
-}
-
-HeapDumpWriter::HeapDumpWriter(StackFrameDeduplicator* stack_frame_deduplicator,
- TypeNameDeduplicator* type_name_deduplicator,
- uint32_t breakdown_threshold_bytes)
- : stack_frame_deduplicator_(stack_frame_deduplicator),
- type_name_deduplicator_(type_name_deduplicator),
- breakdown_threshold_bytes_(breakdown_threshold_bytes) {
-}
-
-HeapDumpWriter::~HeapDumpWriter() {}
-
-bool HeapDumpWriter::AddEntryForBucket(const Bucket& bucket) {
- // The contexts in the bucket are all different, but the [begin, cursor) range
- // is equal for all contexts in the bucket, and the type names are the same if
- // |is_broken_down_by_type_name| is set.
- DCHECK(!bucket.metrics_by_context.empty());
-
- const AllocationContext* context = bucket.metrics_by_context.front().first;
-
- const StackFrame* backtrace_begin = std::begin(context->backtrace.frames);
- const StackFrame* backtrace_end = backtrace_begin + bucket.backtrace_cursor;
- DCHECK_LE(bucket.backtrace_cursor, arraysize(context->backtrace.frames));
-
- Entry entry;
- entry.stack_frame_id = stack_frame_deduplicator_->Insert(
- backtrace_begin, backtrace_end);
-
- // Deduplicate the type name, or use ID -1 if type name is not set.
- entry.type_id = bucket.is_broken_down_by_type_name
- ? type_name_deduplicator_->Insert(context->type_name)
- : -1;
-
- entry.size = bucket.size;
- entry.count = bucket.count;
-
- auto position_and_inserted = entries_.insert(entry);
- return position_and_inserted.second;
-}
-
-void HeapDumpWriter::BreakDown(const Bucket& bucket) {
- auto by_backtrace = BreakDownBy(bucket,
- BreakDownMode::kByBacktrace,
- breakdown_threshold_bytes_);
- auto by_type_name = BreakDownBy(bucket,
- BreakDownMode::kByTypeName,
- breakdown_threshold_bytes_);
-
- // Insert entries for the buckets. If a bucket was not present before, it has
- // not been broken down before, so recursively continue breaking down in that
- // case. There might be multiple routes to the same entry (first break down
- // by type name, then by backtrace, or first by backtrace and then by type),
- // so a set is used to avoid dumping and breaking down entries more than once.
-
- for (const Bucket& subbucket : by_backtrace)
- if (AddEntryForBucket(subbucket))
- BreakDown(subbucket);
-
- for (const Bucket& subbucket : by_type_name)
- if (AddEntryForBucket(subbucket))
- BreakDown(subbucket);
-}
-
-const std::set<Entry>& HeapDumpWriter::Summarize(
- const std::unordered_map<AllocationContext, AllocationMetrics>&
- metrics_by_context) {
- // Start with one bucket that represents the entire heap. Iterate by
- // reference, because the allocation contexts are going to point to allocation
- // contexts stored in |metrics_by_context|.
- Bucket root_bucket;
- for (const auto& context_and_metrics : metrics_by_context) {
- DCHECK_GT(context_and_metrics.second.size, 0u);
- DCHECK_GT(context_and_metrics.second.count, 0u);
- const AllocationContext* context = &context_and_metrics.first;
- root_bucket.metrics_by_context.push_back(
- std::make_pair(context, context_and_metrics.second));
- root_bucket.size += context_and_metrics.second.size;
- root_bucket.count += context_and_metrics.second.count;
- }
-
- AddEntryForBucket(root_bucket);
-
- // Recursively break down the heap and fill |entries_| with entries to dump.
- BreakDown(root_bucket);
-
- return entries_;
-}
-
-std::unique_ptr<TracedValue> Serialize(const std::set<Entry>& entries) {
- std::string buffer;
- std::unique_ptr<TracedValue> traced_value(new TracedValue);
-
- traced_value->BeginArray("entries");
-
- for (const Entry& entry : entries) {
- traced_value->BeginDictionary();
-
- // Format size as hexadecimal string into |buffer|.
- SStringPrintf(&buffer, "%" PRIx64, static_cast<uint64_t>(entry.size));
- traced_value->SetString("size", buffer);
-
- SStringPrintf(&buffer, "%" PRIx64, static_cast<uint64_t>(entry.count));
- traced_value->SetString("count", buffer);
-
- if (entry.stack_frame_id == -1) {
- // An empty backtrace (which will have ID -1) is represented by the empty
- // string, because there is no leaf frame to reference in |stackFrames|.
- traced_value->SetString("bt", "");
- } else {
- // Format index of the leaf frame as a string, because |stackFrames| is a
- // dictionary, not an array.
- SStringPrintf(&buffer, "%i", entry.stack_frame_id);
- traced_value->SetString("bt", buffer);
- }
-
- // Type ID -1 (cumulative size for all types) is represented by the absence
- // of the "type" key in the dictionary.
- if (entry.type_id != -1) {
- // Format the type ID as a string.
- SStringPrintf(&buffer, "%i", entry.type_id);
- traced_value->SetString("type", buffer);
- }
-
- traced_value->EndDictionary();
- }
-
- traced_value->EndArray(); // "entries"
- return traced_value;
-}
-
-} // namespace internal
-
-std::unique_ptr<TracedValue> ExportHeapDump(
- const std::unordered_map<AllocationContext, AllocationMetrics>&
- metrics_by_context,
- const HeapProfilerSerializationState& heap_profiler_serialization_state) {
- internal::HeapDumpWriter writer(
- heap_profiler_serialization_state.stack_frame_deduplicator(),
- heap_profiler_serialization_state.type_name_deduplicator(),
- heap_profiler_serialization_state
- .heap_profiler_breakdown_threshold_bytes());
- return Serialize(writer.Summarize(metrics_by_context));
-}
-
-} // namespace trace_event
-} // namespace base
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