diff options
| -rw-r--r-- | include/fmq/MessageQueue.h | 49 |
1 files changed, 32 insertions, 17 deletions
diff --git a/include/fmq/MessageQueue.h b/include/fmq/MessageQueue.h index e80348d..848b77f 100644 --- a/include/fmq/MessageQueue.h +++ b/include/fmq/MessageQueue.h @@ -130,12 +130,14 @@ struct MessageQueue { * The method will return false without blocking if any of the following * conditions are true: * - If 'evFlag' is nullptr and the FMQ does not own an EventFlag object. - * - If the flavor of the FMQ is synchronized and the 'readNotification' bit mask is zero. + * - If the 'readNotification' bit mask is zero. * - If 'count' is greater than the FMQ size. * - * If the flavor of the FMQ is synchronized and there is insufficient space - * available to write into it, the EventFlag bit mask 'readNotification' is - * is waited upon. + * If the there is insufficient space available to write into it, the + * EventFlag bit mask 'readNotification' is is waited upon. + * + * This method should only be used with a MessageQueue of the flavor + * 'kSynchronizedReadWrite'. * * Upon a successful write, wake is called on 'writeNotification' (if * non-zero). @@ -186,6 +188,9 @@ struct MessageQueue { * -If the 'writeNotification' bit mask is zero. * -If 'count' is greater than the FMQ size. * + * This method should only be used with a MessageQueue of the flavor + * 'kSynchronizedReadWrite'. + * If FMQ does not contain 'count' items, the eventFlag bit mask * 'writeNotification' is waited upon. Upon a successful read from the FMQ, * wake is called on 'readNotification' (if non-zero). @@ -425,10 +430,10 @@ private: enum DefaultEventNotification : uint32_t { /* - * These are only used internally by the blockingRead()/blockingWrite() + * These are only used internally by the readBlocking()/writeBlocking() * methods and hence once other bit combinations are not required. */ - FMQ_NOT_FULL = 0x01, + FMQ_NOT_FULL = 0x01, FMQ_NOT_EMPTY = 0x02 }; @@ -729,6 +734,9 @@ bool MessageQueue<T, flavor>::writeBlocking(const T* data, uint32_t writeNotification, int64_t timeOutNanos, android::hardware::EventFlag* evFlag) { + static_assert(flavor == kSynchronizedReadWrite, + "writeBlocking can only be used with the " + "kSynchronizedReadWrite flavor."); /* * If evFlag is null and the FMQ does not have its own EventFlag object * return false; @@ -740,25 +748,25 @@ bool MessageQueue<T, flavor>::writeBlocking(const T* data, if (evFlag == nullptr) { evFlag = mEventFlag; if (evFlag == nullptr) { + details::logError( + "writeBlocking failed: called on MessageQueue with no Eventflag" + "configured or provided"); return false; } } - if ((readNotification == 0 && flavor == kSynchronizedReadWrite) || - (count > getQuantumCount())) { + if (readNotification == 0 || (count > getQuantumCount())) { return false; } /* - * There is no need to wait for a readNotification if the flavor - * of the queue is kUnsynchronizedWrite or sufficient space to write - * is already present in the FMQ. The latter would be the case when - * read operations read more number of messages than - * write operations write. In other words, a single large read may clear the FMQ - * after multiple small writes. This would fail to clear a pending - * readNotification bit since EventFlag bits can only be cleared - * by a wait() call, however the bit would be correctly cleared by the next - * blockingWrite() call. + * There is no need to wait for a readNotification if there is sufficient + * space to write is already present in the FMQ. The latter would be the case when + * read operations read more number of messages than write operations write. + * In other words, a single large read may clear the FMQ after multiple small + * writes. This would fail to clear a pending readNotification bit since + * EventFlag bits can only be cleared by a wait() call, however the bit would + * be correctly cleared by the next writeBlocking() call. */ bool result = write(data, count); @@ -847,6 +855,10 @@ bool MessageQueue<T, flavor>::readBlocking(T* data, uint32_t writeNotification, int64_t timeOutNanos, android::hardware::EventFlag* evFlag) { + static_assert(flavor == kSynchronizedReadWrite, + "readBlocking can only be used with the " + "kSynchronizedReadWrite flavor."); + /* * If evFlag is null and the FMQ does not own its own EventFlag object * return false; @@ -857,6 +869,9 @@ bool MessageQueue<T, flavor>::readBlocking(T* data, if (evFlag == nullptr) { evFlag = mEventFlag; if (evFlag == nullptr) { + details::logError( + "readBlocking failed: called on MessageQueue with no Eventflag" + "configured or provided"); return false; } } |