projects / thirdparty / squid.git / blame
| Commit | Line | Data |
|---|---|---|
| 8ff3fa2e | 1 | /* |
| b8ae064d | 2 | * Copyright (C) 1996-2023 The Squid Software Foundation and contributors |
| 8ff3fa2e | 3 | * |
| bbc27441 AJ |
4 | * Squid software is distributed under GPLv2+ license and includes |
| 5 | * contributions from numerous individuals and organizations. | |
| 6 | * Please see the COPYING and CONTRIBUTORS files for details. | |
| 8ff3fa2e | 7 | */ |
| 8 | ||
| ff9d9458 FC |
9 | #ifndef SQUID_SRC_ASYNCENGINE_H |
| 10 | #define SQUID_SRC_ASYNCENGINE_H | |
| 8ff3fa2e | 11 | |
| 8ff3fa2e | 12 | /* Abstract interface for async engines which an event loop can utilise. |
| 13 | * | |
| 2f8abb64 | 14 | * Some implementations will be truly async, others like the event engine |
| 8ff3fa2e | 15 | * will be pseudo async. |
| 16 | */ | |
| 17 | ||
| 18 | class AsyncEngine | |
| 19 | { | |
| 20 | ||
| 21 | public: | |
| 22 | /* error codes returned from checkEvents. If the return value is not | |
| 23 | * negative, then it is the requested delay until the next call. If it is | |
| 24 | * negative, it is one of the following codes: | |
| 25 | */ | |
| 26 | enum CheckError { | |
| 27 | /* this engine is completely idle: it has no pending events, and nothing | |
| 28 | * registered with it that can create events | |
| 29 | */ | |
| 30 | EVENT_IDLE = -1, | |
| 61beade2 | 31 | /* some error has occurred in this engine */ |
| ffb809be | 32 | EVENT_ERROR = -2 |
| 8ff3fa2e | 33 | }; |
| 34 | ||
| 35 | virtual ~AsyncEngine() {} | |
| 36 | ||
| 37 | /* Check the engine for events. If there are events that have completed, | |
| 38 | * the engine should at this point hand them off to their dispatcher. | |
| 26ac0430 | 39 | * Engines that operate asynchronously - i.e. the DiskThreads engine - |
| 8ff3fa2e | 40 | * should hand events off to their dispatcher as they arrive rather than |
| 41 | * waiting for checkEvents to be called. Engines like poll and select should | |
| 42 | * use this call as the time to perform their checks with the OS for new | |
| 43 | * events. | |
| 44 | * | |
| 45 | * The return value is the status code of the event checking. If its a | |
| 46 | * non-negative value then it is used as hint for the minimum requested | |
| 47 | * time before checkEvents is called again. I.e. the event engine knows | |
| 26ac0430 | 48 | * how long it is until the next event will be scheduled - so it will |
| 8ff3fa2e | 49 | * return that time (in milliseconds). |
| 50 | * | |
| 51 | * The timeout value is a requested timeout for this engine - the engine | |
| 52 | * should not block for more than this period. (If it takes longer than the | |
| 2f8abb64 | 53 | * timeout to do actual checks that's fine though undesirable). |
| 8ff3fa2e | 54 | */ |
| 55 | virtual int checkEvents(int timeout) = 0; | |
| 56 | }; | |
| 57 | ||
| ff9d9458 | 58 | #endif /* SQUID_SRC_ASYNCENGINE_H */ |
| f53969cc | 59 |