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Commit 78158db5 authored by Dan Egnor's avatar Dan Egnor
Browse files

Hail-Mary attempt to avoid apparent blocking problems in readEvents(). 

Use the same procedure (select() with a short timeout) used by "logcat -d",
which doesn't seem to have any blocking problems.

Bug: 2569403
Change-Id: Ia27bb4207919a1288716b41a007b4b4b52f8e90a
parent 70c294b2

core/jni/android_util_EventLog.cpp

+22 −4
Original line number Diff line number Diff line
@@ -165,14 +165,32 @@ static void android_util_EventLog_readEvents(JNIEnv* env, jobject clazz, 
    jint *tagValues = env->GetIntArrayElements(tags, NULL);



    uint8_t buf[LOGGER_ENTRY_MAX_LEN];

    struct timeval timeout = {0, 0};

    fd_set readset;

    FD_ZERO(&readset);



    for (;;) {

        // Use a short select() to try to avoid problems hanging on read().

        // This means we block for 5ms at the end of the log -- oh well.

        timeout.tv_usec = 5000;

        FD_SET(fd, &readset);

        int r = select(fd + 1, &readset, NULL, NULL, &timeout);

        if (r == 0) {

            break;  // no more events

        } else if (r < 0 && errno == EINTR) {

            continue;  // interrupted by signal, try again

        } else if (r < 0) {

            jniThrowIOException(env, errno);  // Will throw on return

            break;

        }



        int len = read(fd, buf, sizeof(buf));

        if (len == 0 || (len < 0 && errno == EAGAIN)) {

            break;

            break;  // no more events

        } else if (len < 0 && errno == EINTR) {

            continue;  // interrupted by signal, try again

        } else if (len < 0) {

            // This calls env->ThrowNew(), which doesn't throw an exception

            // now, but sets a flag to trigger an exception after we return.

            jniThrowIOException(env, errno);

            jniThrowIOException(env, errno);  // Will throw on return

            break;

        } else if ((size_t) len < sizeof(logger_entry) + sizeof(int32_t)) {

            jniThrowException(env, "java/io/IOException", "Event too short");