gecko-dev/js/public/Initialization.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* SpiderMonkey initialization and shutdown APIs. */

#ifndef js_Initialization_h
#define js_Initialization_h

#include "jstypes.h"

namespace JS {
namespace detail {

enum class InitState {
    Uninitialized = 0,
    Initializing,
    Running,
    ShutDown
};

/**
 * SpiderMonkey's initialization status is tracked here, and it controls things
 * that should happen only once across all runtimes.  It's an API requirement
 * that JS_Init (and JS_ShutDown, if called) be called in a thread-aware
 * manner, so this (internal -- embedders, don't use!) variable doesn't need to
 * be atomic.
 */
extern JS_PUBLIC_DATA(InitState)
libraryInitState;

extern JS_PUBLIC_API(const char*)
InitWithFailureDiagnostic(bool isDebugBuild);

} // namespace detail
} // namespace JS

// These are equivalent to ICU's |UMemAllocFn|, |UMemReallocFn|, and
// |UMemFreeFn| types.  The first argument (called |context| in the ICU docs)
// will always be nullptr and should be ignored.
typedef void* (*JS_ICUAllocFn)(const void*, size_t size);
typedef void* (*JS_ICUReallocFn)(const void*, void* p, size_t size);
typedef void (*JS_ICUFreeFn)(const void*, void* p);

/**
 * This function can be used to track memory used by ICU.  If it is called, it
 * *must* be called before JS_Init.  Don't use it unless you know what you're
 * doing!
 */
extern JS_PUBLIC_API(bool)
JS_SetICUMemoryFunctions(JS_ICUAllocFn allocFn,
                         JS_ICUReallocFn reallocFn,
                         JS_ICUFreeFn freeFn);

#ifdef ENABLE_BIGINT
namespace JS {

// These types are documented as allocate_function, reallocate_function,
// and free_function in the Info node `(gmp)Custom Allocation`.
using GMPAllocFn = void* (*)(size_t allocSize);
using GMPReallocFn = void* (*)(void* p, size_t oldSize, size_t newSize);
using GMPFreeFn = void (*)(void* p, size_t size);

// This function can be used to track memory used by GMP. If it is
// called, it *must* be called before JS_Init so that same functions are
// used for all allocations.
extern JS_PUBLIC_API(void)
SetGMPMemoryFunctions(GMPAllocFn allocFn,
                      GMPReallocFn reallocFn,
                      GMPFreeFn freeFn);

}; // namespace JS
#endif

/**
 * Initialize SpiderMonkey, returning true only if initialization succeeded.
 * Once this method has succeeded, it is safe to call JS_NewContext and other
 * JSAPI methods.
 *
 * This method must be called before any other JSAPI method is used on any
 * thread.  Once it has been used, it is safe to call any JSAPI method, and it
 * remains safe to do so until JS_ShutDown is correctly called.
 *
 * It is currently not possible to initialize SpiderMonkey multiple times (that
 * is, calling JS_Init/JSAPI methods/JS_ShutDown in that order, then doing so
 * again).  This restriction may eventually be lifted.
 */
inline bool
JS_Init(void)
{
#ifdef DEBUG
    return !JS::detail::InitWithFailureDiagnostic(true);
#else
    return !JS::detail::InitWithFailureDiagnostic(false);
#endif
}

/**
 * A variant of JS_Init. On success it returns nullptr. On failure it returns a
 * pointer to a string literal that describes how initialization failed, which
 * can be useful for debugging purposes.
 */
inline const char*
JS_InitWithFailureDiagnostic(void)
{
#ifdef DEBUG
    return JS::detail::InitWithFailureDiagnostic(true);
#else
    return JS::detail::InitWithFailureDiagnostic(false);
#endif
}

/*
 * Returns true if SpiderMonkey has been initialized successfully, even if it has
 * possibly been shut down.
 *
 * Note that it is the responsibility of the embedder to call JS_Init() and
 * JS_ShutDown() at the correct times, and therefore this API should ideally not
 * be necessary to use.  This is only intended to be used in cases where the
 * embedder isn't in full control of deciding whether to initialize SpiderMonkey
 * or hand off the task to another consumer.
 */
inline bool
JS_IsInitialized(void)
{
  return JS::detail::libraryInitState >= JS::detail::InitState::Running;
}

/**
 * Destroy free-standing resources allocated by SpiderMonkey, not associated
 * with any runtime, context, or other structure.
 *
 * This method should be called after all other JSAPI data has been properly
 * cleaned up: every new runtime must have been destroyed, every new context
 * must have been destroyed, and so on.  Calling this method before all other
 * resources have been destroyed has undefined behavior.
 *
 * Failure to call this method, at present, has no adverse effects other than
 * leaking memory.  This may not always be the case; it's recommended that all
 * embedders call this method when all other JSAPI operations have completed.
 *
 * It is currently not possible to initialize SpiderMonkey multiple times (that
 * is, calling JS_Init/JSAPI methods/JS_ShutDown in that order, then doing so
 * again).  This restriction may eventually be lifted.
 */
extern JS_PUBLIC_API(void)
JS_ShutDown(void);

#endif /* js_Initialization_h */