// 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.
#ifndef SkTraceEventCommon_DEFINED
#define SkTraceEventCommon_DEFINED

// This header file defines the set of trace_event macros without specifying
// how the events actually get collected and stored. If you need to expose trace
// events to some other universe, you can copy-and-paste this file as well as
// trace_event.h, modifying the macros contained there as necessary for the
// target platform. The end result is that multiple libraries can funnel events
// through to a shared trace event collector.

// IMPORTANT: To avoid conflicts, if you need to modify this file for a library,
// land your change in base/ first, and then copy-and-paste it.

// Trace events are for tracking application performance and resource usage.
// Macros are provided to track:
//    Begin and end of function calls
//    Counters
//
// Events are issued against categories. Whereas LOG's
// categories are statically defined, TRACE categories are created
// implicitly with a string. For example:
//   TRACE_EVENT_INSTANT0("MY_SUBSYSTEM", "SomeImportantEvent",
//                        TRACE_EVENT_SCOPE_THREAD)
//
// It is often the case that one trace may belong in multiple categories at the
// same time. The first argument to the trace can be a comma-separated list of
// categories, forming a category group, like:
//
// TRACE_EVENT_INSTANT0("input,views", "OnMouseOver", TRACE_EVENT_SCOPE_THREAD)
//
// We can enable/disable tracing of OnMouseOver by enabling/disabling either
// category.
//
// Events can be INSTANT, or can be pairs of BEGIN and END in the same scope:
//   TRACE_EVENT_BEGIN0("MY_SUBSYSTEM", "SomethingCostly")
//   doSomethingCostly()
//   TRACE_EVENT_END0("MY_SUBSYSTEM", "SomethingCostly")
// Note: our tools can't always determine the correct BEGIN/END pairs unless
// these are used in the same scope. Use ASYNC_BEGIN/ASYNC_END macros if you
// need them to be in separate scopes.
//
// A common use case is to trace entire function scopes. This
// issues a trace BEGIN and END automatically:
//   void doSomethingCostly() {
//     TRACE_EVENT0("MY_SUBSYSTEM", "doSomethingCostly");
//     ...
//   }
//
// Additional parameters can be associated with an event:
//   void doSomethingCostly2(int howMuch) {
//     TRACE_EVENT1("MY_SUBSYSTEM", "doSomethingCostly",
//         "howMuch", howMuch);
//     ...
//   }
//
// The trace system will automatically add to this information the
// current process id, thread id, and a timestamp in microseconds.
//
// To trace an asynchronous procedure such as an IPC send/receive, use
// ASYNC_BEGIN and ASYNC_END:
//   [single threaded sender code]
//     static int send_count = 0;
//     ++send_count;
//     TRACE_EVENT_ASYNC_BEGIN0("ipc", "message", send_count);
//     Send(new MyMessage(send_count));
//   [receive code]
//     void OnMyMessage(send_count) {
//       TRACE_EVENT_ASYNC_END0("ipc", "message", send_count);
//     }
// The third parameter is a unique ID to match ASYNC_BEGIN/ASYNC_END pairs.
// ASYNC_BEGIN and ASYNC_END can occur on any thread of any traced process.
// Pointers can be used for the ID parameter, and they will be mangled
// internally so that the same pointer on two different processes will not
// match. For example:
//   class MyTracedClass {
//    public:
//     MyTracedClass() {
//       TRACE_EVENT_ASYNC_BEGIN0("category", "MyTracedClass", this);
//     }
//     ~MyTracedClass() {
//       TRACE_EVENT_ASYNC_END0("category", "MyTracedClass", this);
//     }
//   }
//
// Trace event also supports counters, which is a way to track a quantity
// as it varies over time. Counters are created with the following macro:
//   TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter", g_myCounterValue);
//
// Counters are process-specific. The macro itself can be issued from any
// thread, however.
//
// Sometimes, you want to track two counters at once. You can do this with two
// counter macros:
//   TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter0", g_myCounterValue[0]);
//   TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter1", g_myCounterValue[1]);
// Or you can do it with a combined macro:
//   TRACE_COUNTER2("MY_SUBSYSTEM", "myCounter",
//       "bytesPinned", g_myCounterValue[0],
//       "bytesAllocated", g_myCounterValue[1]);
// This indicates to the tracing UI that these counters should be displayed
// in a single graph, as a summed area chart.
//
// Since counters are in a global namespace, you may want to disambiguate with a
// unique ID, by using the TRACE_COUNTER_ID* variations.
//
// By default, trace collection is compiled in, but turned off at runtime.
// Collecting trace data is the responsibility of the embedding
// application. In Chrome's case, navigating to about:tracing will turn on
// tracing and display data collected across all active processes.
//
//
// Memory scoping note:
// Tracing copies the pointers, not the string content, of the strings passed
// in for category_group, name, and arg_names.  Thus, the following code will
// cause problems:
//     char* str = strdup("importantName");
//     TRACE_EVENT_INSTANT0("SUBSYSTEM", str);  // BAD!
//     free(str);                   // Trace system now has dangling pointer
//
// To avoid this issue with the |name| and |arg_name| parameters, use the
// TRACE_EVENT_COPY_XXX overloads of the macros at additional runtime overhead.
// Notes: The category must always be in a long-lived char* (i.e. static const).
//        The |arg_values|, when used, are always deep copied with the _COPY
//        macros.
//
// When are string argument values copied:
// const char* arg_values are only referenced by default:
//     TRACE_EVENT1("category", "name",
//                  "arg1", "literal string is only referenced");
// Use TRACE_STR_COPY to force copying of a const char*:
//     TRACE_EVENT1("category", "name",
//                  "arg1", TRACE_STR_COPY("string will be copied"));
// std::string arg_values are always copied:
//     TRACE_EVENT1("category", "name",
//                  "arg1", std::string("string will be copied"));
//
//
// Convertable notes:
// Converting a large data type to a string can be costly. To help with this,
// the trace framework provides an interface ConvertableToTraceFormat. If you
// inherit from it and implement the AppendAsTraceFormat method the trace
// framework will call back to your object to convert a trace output time. This
// means, if the category for the event is disabled, the conversion will not
// happen.
//
//   class MyData : public base::trace_event::ConvertableToTraceFormat {
//    public:
//     MyData() {}
//     void AppendAsTraceFormat(std::string* out) const override {
//       out->append("{\"foo\":1}");
//     }
//    private:
//     ~MyData() override {}
//     DISALLOW_COPY_AND_ASSIGN(MyData);
//   };
//
//   TRACE_EVENT1("foo", "bar", "data",
//                scoped_refptr<ConvertableToTraceFormat>(new MyData()));
//
// The trace framework will take ownership if the passed pointer and it will
// be free'd when the trace buffer is flushed.
//
// Note, we only do the conversion when the buffer is flushed, so the provided
// data object should not be modified after it's passed to the trace framework.
//
//
// Thread Safety:
// A thread safe singleton and mutex are used for thread safety. Category
// enabled flags are used to limit the performance impact when the system
// is not enabled.
//
// TRACE_EVENT macros first cache a pointer to a category. The categories are
// statically allocated and safe at all times, even after exit. Fetching a
// category is protected by the TraceLog::lock_. Multiple threads initializing
// the static variable is safe, as they will be serialized by the lock and
// multiple calls will return the same pointer to the category.
//
// Then the category_group_enabled flag is checked. This is a unsigned char, and
// not intended to be multithread safe. It optimizes access to AddTraceEvent
// which is threadsafe internally via TraceLog::lock_. The enabled flag may
// cause some threads to incorrectly call or skip calling AddTraceEvent near
// the time of the system being enabled or disabled. This is acceptable as
// we tolerate some data loss while the system is being enabled/disabled and
// because AddTraceEvent is threadsafe internally and checks the enabled state
// again under lock.
//
// Without the use of these static category pointers and enabled flags all
// trace points would carry a significant performance cost of acquiring a lock
// and resolving the category.

#if defined(TRACE_EVENT0)
#error "Another copy of this file has already been included."
#endif

// This will mark the trace event as disabled by default. The user will need
// to explicitly enable the event.
#define TRACE_DISABLED_BY_DEFAULT(name) "disabled-by-default-" name

// Records a pair of begin and end events called "name" for the current
// scope, with 0, 1 or 2 associated arguments. If the category is not
// enabled, then this does nothing.
// - category and name strings must have application lifetime (statics or
//   literals). They may not include " chars.
#define TRACE_EVENT0(category_group, name)    \
  INTERNAL_TRACE_MEMORY(category_group, name) \
  INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name)

#define TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
  INTERNAL_TRACE_MEMORY(category_group, name)                   \
  INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val)

#define TRACE_EVENT2(category_group, name, arg1_name, arg1_val, arg2_name,   \
                     arg2_val)                                               \
  INTERNAL_TRACE_MEMORY(category_group, name)                                \
  INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val, \
                                  arg2_name, arg2_val)

// Records a single event called "name" immediately, with 0, 1 or 2
// associated arguments. If the category is not enabled, then this
// does nothing.
// - category and name strings must have application lifetime (statics or
//   literals). They may not include " chars.
#define TRACE_EVENT_INSTANT0(category_group, name, scope)                   \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name, \
                           TRACE_EVENT_FLAG_NONE | scope)
#define TRACE_EVENT_INSTANT1(category_group, name, scope, arg1_name, arg1_val) \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name,    \
                           TRACE_EVENT_FLAG_NONE | scope, arg1_name, arg1_val)
#define TRACE_EVENT_INSTANT2(category_group, name, scope, arg1_name, arg1_val, \
                             arg2_name, arg2_val)                              \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name,    \
                           TRACE_EVENT_FLAG_NONE | scope, arg1_name, arg1_val, \
                           arg2_name, arg2_val)
#define TRACE_EVENT_COPY_INSTANT0(category_group, name, scope)              \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name, \
                           TRACE_EVENT_FLAG_COPY | scope)
#define TRACE_EVENT_COPY_INSTANT1(category_group, name, scope, arg1_name,   \
                                  arg1_val)                                 \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name, \
                           TRACE_EVENT_FLAG_COPY | scope, arg1_name, arg1_val)
#define TRACE_EVENT_COPY_INSTANT2(category_group, name, scope, arg1_name,      \
                                  arg1_val, arg2_name, arg2_val)               \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name,    \
                           TRACE_EVENT_FLAG_COPY | scope, arg1_name, arg1_val, \
                           arg2_name, arg2_val)

// Records the value of a counter called "name" immediately. Value
// must be representable as a 32 bit integer.
// - category and name strings must have application lifetime (statics or
//   literals). They may not include " chars.
#define TRACE_COUNTER1(category_group, name, value)                         \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, name, \
                           TRACE_EVENT_FLAG_NONE, "value",                  \
                           static_cast<int>(value))
#define TRACE_COPY_COUNTER1(category_group, name, value)                    \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, name, \
                           TRACE_EVENT_FLAG_COPY, "value",                  \
                           static_cast<int>(value))

// Records the values of a multi-parted counter called "name" immediately.
// The UI will treat value1 and value2 as parts of a whole, displaying their
// values as a stacked-bar chart.
// - category and name strings must have application lifetime (statics or
//   literals). They may not include " chars.
#define TRACE_COUNTER2(category_group, name, value1_name, value1_val,       \
                       value2_name, value2_val)                             \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, name, \
                           TRACE_EVENT_FLAG_NONE, value1_name,              \
                           static_cast<int>(value1_val), value2_name,       \
                           static_cast<int>(value2_val))
#define TRACE_COPY_COUNTER2(category_group, name, value1_name, value1_val,  \
                            value2_name, value2_val)                        \
  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, name, \
                           TRACE_EVENT_FLAG_COPY, value1_name,              \
                           static_cast<int>(value1_val), value2_name,       \
                           static_cast<int>(value2_val))

// Macro to efficiently determine if a given category group is enabled.
#define TRACE_EVENT_CATEGORY_GROUP_ENABLED(category_group, ret)             \
  do {                                                                      \
    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                 \
    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
      *ret = true;                                                          \
    } else {                                                                \
      *ret = false;                                                         \
    }                                                                       \
  } while (0)

// Macro to efficiently determine, through polling, if a new trace has begun.
#define TRACE_EVENT_IS_NEW_TRACE(ret)                                      \
  do {                                                                     \
    static int INTERNAL_TRACE_EVENT_UID(lastRecordingNumber) = 0;          \
    int num_traces_recorded = TRACE_EVENT_API_GET_NUM_TRACES_RECORDED();   \
    if (num_traces_recorded != -1 &&                                       \
        num_traces_recorded !=                                             \
            INTERNAL_TRACE_EVENT_UID(lastRecordingNumber)) {               \
      INTERNAL_TRACE_EVENT_UID(lastRecordingNumber) = num_traces_recorded; \
      *ret = true;                                                         \
    } else {                                                               \
      *ret = false;                                                        \
    }                                                                      \
  } while (0)

// Notes regarding the following definitions:
// New values can be added and propagated to third party libraries, but existing
// definitions must never be changed, because third party libraries may use old
// definitions.

// Phase indicates the nature of an event entry. E.g. part of a begin/end pair.
#define TRACE_EVENT_PHASE_BEGIN ('B')
#define TRACE_EVENT_PHASE_END ('E')
#define TRACE_EVENT_PHASE_COMPLETE ('X')
#define TRACE_EVENT_PHASE_INSTANT ('I')
#define TRACE_EVENT_PHASE_ASYNC_BEGIN ('S')
#define TRACE_EVENT_PHASE_ASYNC_STEP_INTO ('T')
#define TRACE_EVENT_PHASE_ASYNC_STEP_PAST ('p')
#define TRACE_EVENT_PHASE_ASYNC_END ('F')
#define TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN ('b')
#define TRACE_EVENT_PHASE_NESTABLE_ASYNC_END ('e')
#define TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT ('n')
#define TRACE_EVENT_PHASE_FLOW_BEGIN ('s')
#define TRACE_EVENT_PHASE_FLOW_STEP ('t')
#define TRACE_EVENT_PHASE_FLOW_END ('f')
#define TRACE_EVENT_PHASE_METADATA ('M')
#define TRACE_EVENT_PHASE_COUNTER ('C')
#define TRACE_EVENT_PHASE_SAMPLE ('P')
#define TRACE_EVENT_PHASE_CREATE_OBJECT ('N')
#define TRACE_EVENT_PHASE_SNAPSHOT_OBJECT ('O')
#define TRACE_EVENT_PHASE_DELETE_OBJECT ('D')
#define TRACE_EVENT_PHASE_MEMORY_DUMP ('v')
#define TRACE_EVENT_PHASE_MARK ('R')

// Flags for changing the behavior of TRACE_EVENT_API_ADD_TRACE_EVENT.
#define TRACE_EVENT_FLAG_NONE (static_cast<unsigned int>(0))
#define TRACE_EVENT_FLAG_COPY (static_cast<unsigned int>(1 << 0))
#define TRACE_EVENT_FLAG_HAS_ID (static_cast<unsigned int>(1 << 1))
#define TRACE_EVENT_FLAG_MANGLE_ID (static_cast<unsigned int>(1 << 2))
#define TRACE_EVENT_FLAG_SCOPE_OFFSET (static_cast<unsigned int>(1 << 3))
#define TRACE_EVENT_FLAG_SCOPE_EXTRA (static_cast<unsigned int>(1 << 4))
#define TRACE_EVENT_FLAG_EXPLICIT_TIMESTAMP (static_cast<unsigned int>(1 << 5))
#define TRACE_EVENT_FLAG_ASYNC_TTS (static_cast<unsigned int>(1 << 6))
#define TRACE_EVENT_FLAG_BIND_TO_ENCLOSING (static_cast<unsigned int>(1 << 7))
#define TRACE_EVENT_FLAG_FLOW_IN (static_cast<unsigned int>(1 << 8))
#define TRACE_EVENT_FLAG_FLOW_OUT (static_cast<unsigned int>(1 << 9))
#define TRACE_EVENT_FLAG_HAS_CONTEXT_ID (static_cast<unsigned int>(1 << 10))

#define TRACE_EVENT_FLAG_SCOPE_MASK                          \
  (static_cast<unsigned int>(TRACE_EVENT_FLAG_SCOPE_OFFSET | \
                             TRACE_EVENT_FLAG_SCOPE_EXTRA))

// Type values for identifying types in the TraceValue union.
#define TRACE_VALUE_TYPE_BOOL (static_cast<unsigned char>(1))
#define TRACE_VALUE_TYPE_UINT (static_cast<unsigned char>(2))
#define TRACE_VALUE_TYPE_INT (static_cast<unsigned char>(3))
#define TRACE_VALUE_TYPE_DOUBLE (static_cast<unsigned char>(4))
#define TRACE_VALUE_TYPE_POINTER (static_cast<unsigned char>(5))
#define TRACE_VALUE_TYPE_STRING (static_cast<unsigned char>(6))
#define TRACE_VALUE_TYPE_COPY_STRING (static_cast<unsigned char>(7))
#define TRACE_VALUE_TYPE_CONVERTABLE (static_cast<unsigned char>(8))

// Enum reflecting the scope of an INSTANT event. Must fit within
// TRACE_EVENT_FLAG_SCOPE_MASK.
#define TRACE_EVENT_SCOPE_GLOBAL (static_cast<unsigned char>(0 << 3))
#define TRACE_EVENT_SCOPE_PROCESS (static_cast<unsigned char>(1 << 3))
#define TRACE_EVENT_SCOPE_THREAD (static_cast<unsigned char>(2 << 3))

#define TRACE_EVENT_SCOPE_NAME_GLOBAL ('g')
#define TRACE_EVENT_SCOPE_NAME_PROCESS ('p')
#define TRACE_EVENT_SCOPE_NAME_THREAD ('t')
#endif  // SkTraceEventCommon_DEFINED