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//===-- xray_profile_collector.h -------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of XRay, a dynamic runtime instrumentation system.
//
// This file defines the interface for a data collection service, for XRay
// profiling. What we implement here is an in-process service where
// FunctionCallTrie instances can be handed off by threads, to be
// consolidated/collected.
//
//===----------------------------------------------------------------------===//
#ifndef XRAY_XRAY_PROFILE_COLLECTOR_H
#define XRAY_XRAY_PROFILE_COLLECTOR_H
#include "xray_function_call_trie.h"
#include "xray/xray_log_interface.h"
namespace __xray {
/// The ProfileCollectorService implements a centralised mechanism for
/// collecting FunctionCallTrie instances, indexed by thread ID. On demand, the
/// ProfileCollectorService can be queried for the most recent state of the
/// data, in a form that allows traversal.
namespace profileCollectorService {
/// Posts the FunctionCallTrie associated with a specific Thread ID. This
/// will:
///
/// - Make a copy of the FunctionCallTrie and store that against the Thread
/// ID. This will use the global allocator for the service-managed
/// FunctionCallTrie instances.
/// - Queue up a pointer to the FunctionCallTrie.
/// - If the queue is long enough (longer than some arbitrary threshold) we
/// then pre-calculate a single FunctionCallTrie for the whole process.
///
///
/// We are making a copy of the FunctionCallTrie because the intent is to have
/// this function be called at thread exit, or soon after the profiling
/// handler is finalized through the XRay APIs. By letting threads each
/// process their own thread-local FunctionCallTrie instances, we're removing
/// the need for synchronisation across threads while we're profiling.
/// However, once we're done profiling, we can then collect copies of these
/// FunctionCallTrie instances and pay the cost of the copy.
///
/// NOTE: In the future, if this turns out to be more costly than "moving" the
/// FunctionCallTrie instances from the owning thread to the collector
/// service, then we can change the implementation to do it this way (moving)
/// instead.
void post(const FunctionCallTrie &T, tid_t TId);
/// The serialize will process all FunctionCallTrie instances in memory, and
/// turn those into specifically formatted blocks, each describing the
/// function call trie's contents in a compact form. In memory, this looks
/// like the following layout:
///
/// - block size (32 bits)
/// - block number (32 bits)
/// - thread id (64 bits)
/// - list of records:
/// - function ids in leaf to root order, terminated by
/// 0 (32 bits per function id)
/// - call count (64 bit)
/// - cumulative local time (64 bit)
/// - record delimiter (64 bit, 0x0)
///
void serialize();
/// The reset function will clear out any internal memory held by the
/// service. The intent is to have the resetting be done in calls to the
/// initialization routine, or explicitly through the flush log API.
void reset();
/// This nextBuffer function is meant to implement the iterator functionality,
/// provided in the XRay API.
XRayBuffer nextBuffer(XRayBuffer B);
} // namespace profileCollectorService
} // namespace __xray
#endif // XRAY_XRAY_PROFILE_COLLECTOR_H
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