/** @file * IPRT - Critical Sections. */ /* * Copyright (C) 2006-2011 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the * VirtualBox OSE distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. */ #ifndef ___iprt_critsect_h #define ___iprt_critsect_h #include #include #include #ifdef IN_RING3 # include #endif #ifdef RT_LOCK_STRICT_ORDER # include #endif RT_C_DECLS_BEGIN /** @defgroup grp_rt_critsect RTCritSect - Critical Sections * * "Critical section" synchronization primitives can be used to * protect a section of code or data to which access must be exclusive; * only one thread can hold access to a critical section at one time. * * A critical section is a fast recursive write lock; if the critical * section is not acquired, then entering it is fast (requires no system * call). IPRT uses the Windows terminology here; on other platform, this * might be called a "futex" or a "fast mutex". As opposed to IPRT * "fast mutexes" (see @ref grp_rt_sems_fast_mutex ), critical sections * are recursive. * * Use RTCritSectInit to initialize a critical section; use RTCritSectEnter * and RTCritSectLeave to acquire and release access. * * For an overview of all types of synchronization primitives provided * by IPRT (event, mutex/fast mutex/read-write mutex semaphores), see * @ref grp_rt_sems . * * @ingroup grp_rt * @{ */ /** * Critical section. */ typedef struct RTCRITSECT { /** Magic used to validate the section state. * RTCRITSECT_MAGIC is the value of an initialized & operational section. */ volatile uint32_t u32Magic; /** Number of lockers. * -1 if the section is free. */ volatile int32_t cLockers; /** The owner thread. */ volatile RTNATIVETHREAD NativeThreadOwner; /** Number of nested enter operations performed. * Greater or equal to 1 if owned, 0 when free. */ volatile int32_t cNestings; /** Section flags - the RTCRITSECT_FLAGS_* \#defines. */ uint32_t fFlags; /** The semaphore to block on. */ RTSEMEVENT EventSem; /** Lock validator record. Only used in strict builds. */ R3R0PTRTYPE(PRTLOCKVALRECEXCL) pValidatorRec; /** Alignmnet padding. */ RTHCPTR Alignment; } RTCRITSECT; AssertCompileSize(RTCRITSECT, HC_ARCH_BITS == 32 ? 32 : 48); /** RTCRITSECT::u32Magic value. (Hiromi Uehara) */ #define RTCRITSECT_MAGIC UINT32_C(0x19790326) /** @name RTCritSectInitEx flags / RTCRITSECT::fFlags * @{ */ /** If set, nesting(/recursion) is not allowed. */ #define RTCRITSECT_FLAGS_NO_NESTING UINT32_C(0x00000001) /** Disables lock validation. */ #define RTCRITSECT_FLAGS_NO_LOCK_VAL UINT32_C(0x00000002) /** Bootstrap hack for use with certain memory allocator locks only! */ #define RTCRITSECT_FLAGS_BOOTSTRAP_HACK UINT32_C(0x00000004) /** If set, the critical section becomes a dummy that doesn't serialize any * threads. This flag can only be set at creation time. * * The intended use is avoiding lots of conditional code where some component * might or might not require entering a critical section before access. */ #define RTCRITSECT_FLAGS_NOP UINT32_C(0x00000008) /** @} */ #ifdef IN_RING3 /** * Initialize a critical section. */ RTDECL(int) RTCritSectInit(PRTCRITSECT pCritSect); /** * Initialize a critical section. * * @returns iprt status code. * @param pCritSect Pointer to the critical section structure. * @param fFlags Flags, any combination of the RTCRITSECT_FLAGS * \#defines. * @param hClass The class (no reference consumed). If NIL, no * lock order validation will be performed on this * lock. * @param uSubClass The sub-class. This is used to define lock * order within a class. RTLOCKVAL_SUB_CLASS_NONE * is the recommended value here. * @param pszNameFmt Name format string for the lock validator, * optional (NULL). Max length is 32 bytes. * @param ... Format string arguments. */ RTDECL(int) RTCritSectInitEx(PRTCRITSECT pCritSect, uint32_t fFlags, RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...); /** * Changes the lock validator sub-class of the critical section. * * It is recommended to try make sure that nobody is using this critical section * while changing the value. * * @returns The old sub-class. RTLOCKVAL_SUB_CLASS_INVALID is returns if the * lock validator isn't compiled in or either of the parameters are * invalid. * @param pCritSect The critical section. * @param uSubClass The new sub-class value. */ RTDECL(uint32_t) RTCritSectSetSubClass(PRTCRITSECT pCritSect, uint32_t uSubClass); /** * Enter a critical section. * * @returns VINF_SUCCESS on success. * @returns VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.) * @returns VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting. * @param pCritSect The critical section. */ RTDECL(int) RTCritSectEnter(PRTCRITSECT pCritSect); /** * Enter a critical section. * * @retval VINF_SUCCESS on success. * @retval VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.) * @retval VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting. * * @param pCritSect The critical section. * @param uId Where we're entering the section. * @param pszFile The source position - file. * @param iLine The source position - line. * @param pszFunction The source position - function. */ RTDECL(int) RTCritSectEnterDebug(PRTCRITSECT pCritSect, RTHCUINTPTR uId, RT_SRC_POS_DECL); /** * Try enter a critical section. * * @retval VINF_SUCCESS on success. * @retval VERR_SEM_BUSY if the critsect was owned. * @retval VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.) * @retval VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting. * * @param pCritSect The critical section. */ RTDECL(int) RTCritSectTryEnter(PRTCRITSECT pCritSect); /** * Try enter a critical section. * * @retval VINF_SUCCESS on success. * @retval VERR_SEM_BUSY if the critsect was owned. * @retval VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.) * @retval VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting. * * @param pCritSect The critical section. * @param uId Where we're entering the section. * @param pszFile The source position - file. * @param iLine The source position - line. * @param pszFunction The source position - function. */ RTDECL(int) RTCritSectTryEnterDebug(PRTCRITSECT pCritSect, RTHCUINTPTR uId, RT_SRC_POS_DECL); /** * Enter multiple critical sections. * * This function will enter ALL the specified critical sections before returning. * * @returns VINF_SUCCESS on success. * @returns VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.) * @returns VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting. * @param cCritSects Number of critical sections in the array. * @param papCritSects Array of critical section pointers. * * @remark Please note that this function will not necessarily come out favourable in a * fight with other threads which are using the normal RTCritSectEnter() function. * Therefore, avoid having to enter multiple critical sections! */ RTDECL(int) RTCritSectEnterMultiple(size_t cCritSects, PRTCRITSECT *papCritSects); /** * Enter multiple critical sections. * * This function will enter ALL the specified critical sections before returning. * * @returns VINF_SUCCESS on success. * @returns VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.) * @returns VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting. * * @param cCritSects Number of critical sections in the array. * @param papCritSects Array of critical section pointers. * @param uId Where we're entering the section. * @param pszFile The source position - file. * @param iLine The source position - line. * @param pszFunction The source position - function. * * @remark See RTCritSectEnterMultiple(). */ RTDECL(int) RTCritSectEnterMultipleDebug(size_t cCritSects, PRTCRITSECT *papCritSects, RTUINTPTR uId, RT_SRC_POS_DECL); /** * Leave a critical section. * * @returns VINF_SUCCESS. * @param pCritSect The critical section. */ RTDECL(int) RTCritSectLeave(PRTCRITSECT pCritSect); /** * Leave multiple critical sections. * * @returns VINF_SUCCESS. * @param cCritSects Number of critical sections in the array. * @param papCritSects Array of critical section pointers. */ RTDECL(int) RTCritSectLeaveMultiple(size_t cCritSects, PRTCRITSECT *papCritSects); /** * Deletes a critical section. * * @returns VINF_SUCCESS. * @param pCritSect The critical section. */ RTDECL(int) RTCritSectDelete(PRTCRITSECT pCritSect); /** * Checks the caller is the owner of the critical section. * * @returns true if owner. * @returns false if not owner. * @param pCritSect The critical section. */ DECLINLINE(bool) RTCritSectIsOwner(PCRTCRITSECT pCritSect) { return pCritSect->NativeThreadOwner == RTThreadNativeSelf(); } #endif /* IN_RING3 */ /** * Checks the section is owned by anyone. * * @returns true if owned. * @returns false if not owned. * @param pCritSect The critical section. */ DECLINLINE(bool) RTCritSectIsOwned(PCRTCRITSECT pCritSect) { return pCritSect->NativeThreadOwner != NIL_RTNATIVETHREAD; } /** * Gets the thread id of the critical section owner. * * @returns Thread id of the owner thread if owned. * @returns NIL_RTNATIVETHREAD is not owned. * @param pCritSect The critical section. */ DECLINLINE(RTNATIVETHREAD) RTCritSectGetOwner(PCRTCRITSECT pCritSect) { return pCritSect->NativeThreadOwner; } /** * Checks if a critical section is initialized or not. * * @returns true if initialized. * @returns false if not initialized. * @param pCritSect The critical section. */ DECLINLINE(bool) RTCritSectIsInitialized(PCRTCRITSECT pCritSect) { return pCritSect->u32Magic == RTCRITSECT_MAGIC; } /** * Gets the recursion depth. * * @returns The recursion depth. * @param pCritSect The Critical section */ DECLINLINE(uint32_t) RTCritSectGetRecursion(PCRTCRITSECT pCritSect) { return pCritSect->cNestings; } /** * Gets the waiter count * * @returns The waiter count * @param pCritSect The Critical section */ DECLINLINE(int32_t) RTCritSectGetWaiters(PCRTCRITSECT pCritSect) { return pCritSect->cLockers; } /* Lock strict build: Remap the three enter calls to the debug versions. */ #if defined(RT_LOCK_STRICT) && !defined(RTCRITSECT_WITHOUT_REMAPPING) && !defined(RT_WITH_MANGLING) # ifdef ___iprt_asm_h # define RTCritSectEnter(pCritSect) RTCritSectEnterDebug(pCritSect, (uintptr_t)ASMReturnAddress(), RT_SRC_POS) # define RTCritSectTryEnter(pCritSect) RTCritSectTryEnterDebug(pCritSect, (uintptr_t)ASMReturnAddress(), RT_SRC_POS) # define RTCritSectEnterMultiple(cCritSects, pCritSect) RTCritSectEnterMultipleDebug((cCritSects), (pCritSect), (uintptr_t)ASMReturnAddress(), RT_SRC_POS) # else # define RTCritSectEnter(pCritSect) RTCritSectEnterDebug(pCritSect, 0, RT_SRC_POS) # define RTCritSectTryEnter(pCritSect) RTCritSectTryEnterDebug(pCritSect, 0, RT_SRC_POS) # define RTCritSectEnterMultiple(cCritSects, pCritSect) RTCritSectEnterMultipleDebug((cCritSects), (pCritSect), 0, RT_SRC_POS) # endif #endif /* Strict lock order: Automatically classify locks by init location. */ #if defined(RT_LOCK_STRICT_ORDER) && defined(IN_RING3) && !defined(RTCRITSECT_WITHOUT_REMAPPING) &&!defined(RT_WITH_MANGLING) # define RTCritSectInit(pCritSect) \ RTCritSectInitEx((pCritSect), 0 /*fFlags*/, \ RTLockValidatorClassForSrcPos(RT_SRC_POS, NULL), \ RTLOCKVAL_SUB_CLASS_NONE, NULL) #endif /** @} */ RT_C_DECLS_END #endif