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Unified Diff: base/trace_event/heap_profiler_type_name_deduplicator.cc

Issue 1467453003: [Tracing] Make heap profiler type info a string (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Rebase Created 5 years, 1 month ago
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Index: base/trace_event/heap_profiler_type_name_deduplicator.cc
diff --git a/base/trace_event/heap_profiler_type_name_deduplicator.cc b/base/trace_event/heap_profiler_type_name_deduplicator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..17c3ceee67261acc516eb2d47b29cebe4a295e20
--- /dev/null
+++ b/base/trace_event/heap_profiler_type_name_deduplicator.cc
@@ -0,0 +1,75 @@
+// 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_type_name_deduplicator.h"
+
+#include <stdlib.h>
+#include <string>
+#include <utility>
+
+#include "base/json/string_escape.h"
+#include "base/strings/stringprintf.h"
+#include "base/trace_event/trace_event_memory_overhead.h"
+
+namespace base {
+namespace trace_event {
+
+TypeNameDeduplicator::TypeNameDeduplicator() {
+ // A null pointer has type ID 0 ("unknown type");
+ type_ids_.insert(std::make_pair(nullptr, 0));
+}
+
+TypeNameDeduplicator::~TypeNameDeduplicator() {}
+
+int TypeNameDeduplicator::Insert(const char* type_name) {
+ auto result = type_ids_.insert(std::make_pair(type_name, 0));
+ auto& elem = result.first;
+ bool did_not_exist_before = result.second;
+
+ if (did_not_exist_before) {
+ // The type IDs are assigned sequentially and they are zero-based, so
+ // |size() - 1| is the ID of the new element.
+ elem->second = static_cast<int>(type_ids_.size() - 1);
+ }
+
+ return elem->second;
+}
+
+void TypeNameDeduplicator::AppendAsTraceFormat(std::string* out) const {
+ out->append("{"); // Begin the type names dictionary.
+
+ auto it = type_ids_.begin();
+ std::string buffer;
+
+ // Write the first entry manually; the null pointer must not be dereferenced.
+ // (The first entry is the null pointer because a |std::map| is ordered.)
+ it++;
+ out->append("\"0\":\"[unknown]\"");
+
+ for (; it != type_ids_.end(); it++) {
+ // Type IDs in the trace are strings, write them as stringified keys of
+ // a dictionary.
+ SStringPrintf(&buffer, ",\"%d\":", it->second);
+
+ // |EscapeJSONString| appends, it does not overwrite |buffer|.
+ bool put_in_quotes = true;
+ EscapeJSONString(it->first, put_in_quotes, &buffer);
+ out->append(buffer);
+ }
+
+ out->append("}"); // End the type names dictionary.
+}
+
+void TypeNameDeduplicator::EstimateTraceMemoryOverhead(
+ TraceEventMemoryOverhead* overhead) {
+ // The size here is only an estimate; it fails to take into account the size
+ // of the tree nodes for the map, but as an estimate this should be fine.
+ size_t map_size = type_ids_.size() * sizeof(std::pair<const char*, int>);
+
+ overhead->Add("TypeNameDeduplicator",
+ sizeof(TypeNameDeduplicator) + map_size);
+}
+
+} // namespace trace_event
+} // namespace base

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