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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_DEBUG_TASK_TRACE_H_
#define BASE_DEBUG_TASK_TRACE_H_
#include <iosfwd>
#include <optional>
#include <string>
#include "base/base_export.h"
#include "base/containers/span.h"
#include "base/debug/stack_trace.h"
namespace base {
namespace debug {
// Provides a snapshot of which places in the code called
// base::TaskRunner::PostTask() that led to the TaskTrace() constructor call.
// Analogous to base::StackTrace, but for posted tasks rather than function
// calls.
//
// Example usage:
// TaskTrace().Print();
//
// Example output:
// Task trace:
// #0 content::ServiceWorkerContextWrapper::DidCheckHasServiceWorker()
// #1 content::ServiceWorkerStorage::FindForDocumentInDB()
// #2 content::ServiceWorkerStorage::FindRegistrationForDocument()
// #3 content::ServiceWorkerContextWrapper::CheckHasServiceWorker()
// #4 content::ManifestIconDownloader::ScaleIcon()
// Task trace buffer limit hit, update PendingTask::kTaskBacktraceLength to
// increase.
class BASE_EXPORT TaskTrace {
public:
TaskTrace();
// Whether there is any trace data.
bool empty() const;
// Outputs to stderr via OutputToStream.
void Print() const;
// Outputs trace to |os|, may be called when empty() is true.
void OutputToStream(std::ostream* os) const;
// Resolves trace to symbols and returns as string.
std::string ToString() const;
// Reads the list of addresses currently in the task trace into `addresses`,
// and returns the maximum length of addresses that could have been read,
// which may differ from `addresses.size()`.
size_t GetAddresses(span<const void*> addresses) const;
private:
std::optional<StackTrace> stack_trace_;
bool trace_overflow_ = false;
};
// Forwards to TaskTrace::OutputToStream.
BASE_EXPORT std::ostream& operator<<(std::ostream& os,
const TaskTrace& task_trace);
} // namespace debug
} // namespace base
#endif // BASE_DEBUG_TASK_TRACE_H_
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