// Copyright (C) 2017 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Rafael Roquetto // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #ifndef QTRACE_P_H #define QTRACE_P_H // // W A R N I N G // ------------- // // This file is not part of the Qt API. It exists purely as an // implementation detail. This header file may change from version to // version without notice, or even be removed. // // We mean it. // /* * The Qt tracepoints API consists of only five macros: * * - Q_TRACE(tracepoint, args...) * Fires 'tracepoint' if it is enabled. * * - Q_TRACE_EXIT(tracepoint, args...) * Fires 'tracepoint' if it is enabled when the current scope exists. * * - Q_TRACE_SCOPE(tracepoint, args...) * Wrapper around Q_TRACE/_EXIT to trace entry and exit. First it traces * `${tracepoint}_entry` and then `${tracepoint}_exit` on scope exit. * * - Q_UNCONDITIONAL_TRACE(tracepoint, args...) * Fires 'tracepoint' unconditionally: no check is performed to query * whether 'tracepoint' is enabled. * * - Q_TRACE_ENABLED(tracepoint) * Returns 'true' if 'tracepoint' is enabled; false otherwise. * * When using LTTNG, Q_TRACE, Q_UNCONDITIONAL_TRACE and Q_TRACE_ENABLED map * ultimately to tracepoint(), do_tracepoint() and tracepoint_enabled(), * respectively, described on the lttng-ust manpage (man 3 lttng-ust). * * On ETW, Q_TRACE() and Q_UNCONDITIONAL_TRACE() are equivalent, ultimately * amounting to a call to TraceLoggingWrite(), whereas Q_TRACE_ENABLED() * wraps around TraceLoggingProviderEnabled(). * * A tracepoint provider is defined in a separate file, that follows the * following format: * * tracepoint_name(arg_type arg_name, ...) * * For instance: * * qcoreapplication_ctor(int argc, const char * const argv) * qcoreapplication_foo(int argc, const char[10] argv) * qcoreapplication_baz(const char[len] some_string, unsigned int len) * qcoreapplication_qstring(const QString &foo) * qcoreapplication_qrect(const QRect &rect) * * The provider file is then parsed by src/tools/tracegen, which can be * switched to output either ETW, CTF or LTTNG tracepoint definitions. The provider * name is deduced to be basename(provider_file). * * To use the above (inside qtcore), you need to include * . After that, the following call becomes * possible: * * Q_TRACE(qcoreapplication_qrect, myRect); * * Currently, all C++ primitive non-pointer types are supported for * arguments. Additionally, char * is supported, and is assumed to * be a NULL-terminated string. Finally, the following subset of Qt types also * currently supported: * * - QString * - QByteArray * - QUrl * - QRect * - QRectF * - QSize * - QSizeF * * Dynamic arrays are supported using the syntax illustrated by * qcoreapplication_baz above. * * One can also add prefix for the generated providername_tracepoints_p.h file * by specifying it inside brackets '{ }' in the tracepoints file. One can * for example add forward declaration for a type: * * { * QT_BEGIN_NAMESPACE * class QEvent; * QT_END_NAMESPACE * } * * Metadata * * Metadata is used to add textual information for different types such * as enums and flags. How this data is handled depends on the used backend. * For ETW, the values are converted to text, for CTF and LTTNG they are used to add * CTF enumerations, which are converted to text after tracing. * * Enumererations are specified using ENUM: * * ENUM { * Enum0 = 0, * Enum1 = 1, * Enum2, * RANGE(RangeEnum, 3 ... 10), * } Name; * * Name must match to one of the enumerations used in the tracepoints. Range of values * can be provided using RANGE(name, first ... last). All values must be unique. * * Flags are specified using FLAGS: * * FLAGS { * Default = 0, * Flag0 = 1, * Flag1 = 2, * Flag2 = 4, * } Name; * * Name must match to one of the flags used in the tracepoints. Each value must be * power of two and unique. */ #include #include QT_BEGIN_NAMESPACE #if defined(Q_TRACEPOINT) && !defined(QT_BOOTSTRAPPED) # define Q_HAS_TRACEPOINTS 1 # define Q_TRACE(x, ...) QtPrivate::trace_ ## x(__VA_ARGS__) # define Q_TRACE_EXIT(x, ...) \ const auto qTraceExit_ ## x ## __COUNTER__ = qScopeGuard([&]() { Q_TRACE(x, __VA_ARGS__); }); # define Q_TRACE_SCOPE(x, ...) \ Q_TRACE(x ## _entry, __VA_ARGS__); \ Q_TRACE_EXIT(x ## _exit); # define Q_UNCONDITIONAL_TRACE(x, ...) QtPrivate::do_trace_ ## x(__VA_ARGS__) # define Q_TRACE_ENABLED(x) QtPrivate::trace_ ## x ## _enabled() #else # define Q_HAS_TRACEPOINTS 0 # define Q_TRACE(x, ...) # define Q_TRACE_EXIT(x, ...) # define Q_TRACE_SCOPE(x, ...) # define Q_UNCONDITIONAL_TRACE(x, ...) # define Q_TRACE_ENABLED(x) false #endif // defined(Q_TRACEPOINT) && !defined(QT_BOOTSTRAPPED) /* * The Qt tracepoints can also be defined directly in the source files using * the following macros. If using these macros, the tracepoints file is automatically * generated using the tracepointgen tool. The tool scans the input files for * these macros. These macros are ignored during compile time. Both automatic * generation and manually specifying tracepoints in a file can't be done at the same * time for the same provider. * * - Q_TRACE_INSTRUMENT(provider) * Generate entry/exit tracepoints for a function. For example, member function * * void SomeClass::method(int param1, float param2) * { * ... * } * * converted to use tracepoints: * * void Q_TRACE_INSTRUMENT(provider) SomeClass::method(int param1, float param2) * { * Q_TRACE_SCOPE(SomeClass_method, param1, param2); * ... * } * * generates following tracepoints in provider.tracepoints file: * * SomeClass_method_entry(int param1, float param2) * SomeClass_method_exit() * * - Q_TRACE_PARAM_REPLACE(in, out) * Can be used with Q_TRACE_INSTRUMENT to replace parameter type in with type out. * If a parameter type is not supported by the tracegen tool, one can use this to * change it to another supported type. * * void Q_TRACE_INSTRUMENT(provider) SomeClass::method(int param1, UserType param2) * { * Q_TRACE_PARAM_REPLACE(UserType, QString); * Q_TRACE_SCOPE(SomeClass_method, param1, param2.toQString()); * } * * - Q_TRACE_POINT(provider, tracepoint, ...) * Manually specify tracepoint for the provider. 'tracepoint' is the full name * of the tracepoint and ... can be zero or more parameters. * * Q_TRACE_POINT(provider, SomeClass_function_entry, int param1, int param2); * * generates following tracepoint: * * SomeClass_function_entry(int param1, int param2) * * - Q_TRACE_PREFIX(provider, prefix) * Provide prefix for the tracepoint. Multiple prefixes can be specified for the same * provider in different files, they are all concatenated into one in the * provider.tracepoints file. * * Q_TRACE_PREFIX(provider, * "QT_BEGIN_NAMESPACE" \ * "class QEvent;" \ * "QT_END_NAMESPACE") * * - Q_TRACE_METADATA(provider, metadata) * Provides metadata for the tracepoint provider. * * Q_TRACE_METADATA(qtgui, * "ENUM {" \ * "Format_Invalid," \ * "Format_Mono," \ * "Format_MonoLSB," \ * "Format_Indexed8," \ * ... * "} QImage::Format;" \ * ); * * If the content of enum is empty or contains keyword AUTO, then the tracepointgen tool * tries to find the enumeration from header files. * * Q_TRACE_METADATA(qtcore, "ENUM { AUTO, RANGE User ... MaxUser } QEvent::Type;"); */ #define Q_TRACE_INSTRUMENT(provider) #define Q_TRACE_PARAM_REPLACE(in, out) #define Q_TRACE_POINT(provider, tracepoint, ...) #define Q_TRACE_PREFIX(provider, prefix) #define Q_TRACE_METADATA(provider, metadata) QT_END_NAMESPACE #endif // QTRACE_P_H