//--------------------------------------------------------------------------------------------------------------------------------- // File: InterlockedSList.h // // Contents: Contains a portable abstraction for interlocked, singly // linked list. // // Microsoft Drivers 5.10 for PHP for SQL Server // Copyright(c) Microsoft Corporation // All rights reserved. // MIT License // Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files(the ""Software""), // to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, // and / or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions : // The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. // THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS // IN THE SOFTWARE. //--------------------------------------------------------------------------------------------------------------------------------- #ifndef __INTERLOCKEDSLIST_H__ #define __INTERLOCKEDSLIST_H__ #include "interlockedatomic.h" #define SLIST_ENTRY SINGLE_LIST_ENTRY #define PSLIST_ENTRY PSINGLE_LIST_ENTRY typedef struct _SINGLE_LIST_ENTRY { // Want a volatile pointer to non-volatile data so place after all type info struct _SINGLE_LIST_ENTRY * volatile Next; } SINGLE_LIST_ENTRY, *PSINGLE_LIST_ENTRY; typedef union _SLIST_HEADER { // Provides 8 byte alignment for 32-bit builds. Technically, not needed for // current implementation below but leaving for future use. ULONGLONG Alignment; struct { // Want a volatile pointer to non-volatile data so place after all type info PSLIST_ENTRY volatile Head; volatile LONG Depth; volatile LONG Mutex; } List; } SLIST_HEADER, *PSLIST_HEADER; inline VOID InitializeSListHead( PSLIST_HEADER slist ) { assert( NULL != slist ); slist->List.Head = NULL; slist->List.Depth = 0; slist->List.Mutex = 0; } inline PSLIST_ENTRY InterlockedPopEntrySList( PSLIST_HEADER slist ) { assert( NULL != slist ); // Exit prior to 'mutex' if we think it is empty // Some callers (like sqlncli/msdart/dll/dynslist.h) rely on a NULL // result from Pop to indicate the list is empty. This early exit // is an optimization and not technically needed for correctness. PSLIST_ENTRY oldHead = slist->List.Head; if ( NULL == oldHead ) { return NULL; } while ( 0 != slist->List.Mutex || 0 != InterlockedCompareExchange( &slist->List.Mutex, 1, 0 ) ) { // Spin until 'mutex' is free } // We have the 'mutex' so proceed with update oldHead = slist->List.Head; if ( NULL != oldHead ) { slist->List.Head = oldHead->Next; --(slist->List.Depth); assert( 0 <= slist->List.Depth ); } // Free the 'mutex' slist->List.Mutex = 0; return oldHead; } inline PSLIST_ENTRY InterlockedPushEntrySList( PSLIST_HEADER slist, PSLIST_ENTRY newEntry ) { assert( NULL != slist ); while ( 0 != slist->List.Mutex || 0 != InterlockedCompareExchange( &slist->List.Mutex, 1, 0 ) ) { // Spin until 'mutex' is free } // We have the 'mutex' so proceed with update PSLIST_ENTRY oldHead = slist->List.Head; newEntry->Next = oldHead; slist->List.Head = newEntry; ++(slist->List.Depth); // Free the 'mutex' slist->List.Mutex = 0; return oldHead; } inline PSLIST_ENTRY InterlockedFlushSList( PSLIST_HEADER slist ) { assert( NULL != slist ); while ( 0 != slist->List.Mutex || 0 != InterlockedCompareExchange( &slist->List.Mutex, 1, 0 ) ) { // Spin until 'mutex' is free } // We have the 'mutex' so proceed with update PSLIST_ENTRY oldHead = slist->List.Head; slist->List.Head = NULL; slist->List.Depth = 0; // Free the 'mutex' slist->List.Mutex = 0; return oldHead; } // If the list has more than USHORT nodes then this method // will not return reliable results. inline USHORT QueryDepthSList( PSLIST_HEADER slist ) { assert( NULL != slist ); return static_cast(slist->List.Depth); } #endif // __INTERLOCKEDSLIST_H__