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Diffstat (limited to 'contrib/qemu/qemu-coroutine.c')
-rw-r--r-- | contrib/qemu/qemu-coroutine.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/contrib/qemu/qemu-coroutine.c b/contrib/qemu/qemu-coroutine.c new file mode 100644 index 00000000000..423430d3a03 --- /dev/null +++ b/contrib/qemu/qemu-coroutine.c @@ -0,0 +1,135 @@ +/* + * QEMU coroutines + * + * Copyright IBM, Corp. 2011 + * + * Authors: + * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> + * Kevin Wolf <kwolf@redhat.com> + * + * This work is licensed under the terms of the GNU LGPL, version 2 or later. + * See the COPYING.LIB file in the top-level directory. + * + */ + +#include "trace.h" +#include "qemu-common.h" +#include "qemu/thread.h" +#include "block/coroutine.h" +#include "block/coroutine_int.h" + +enum { + /* Maximum free pool size prevents holding too many freed coroutines */ + POOL_MAX_SIZE = 64, +}; + +/** Free list to speed up creation */ +static QemuMutex pool_lock; +static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool); +static unsigned int pool_size; + +Coroutine *qemu_coroutine_create(CoroutineEntry *entry) +{ + Coroutine *co; + + qemu_mutex_lock(&pool_lock); + co = QSLIST_FIRST(&pool); + if (co) { + QSLIST_REMOVE_HEAD(&pool, pool_next); + pool_size--; + } + qemu_mutex_unlock(&pool_lock); + + if (!co) { + co = qemu_coroutine_new(); + } + + co->entry = entry; + QTAILQ_INIT(&co->co_queue_wakeup); + return co; +} + +static void coroutine_delete(Coroutine *co) +{ + qemu_mutex_lock(&pool_lock); + if (pool_size < POOL_MAX_SIZE) { + QSLIST_INSERT_HEAD(&pool, co, pool_next); + co->caller = NULL; + pool_size++; + qemu_mutex_unlock(&pool_lock); + return; + } + qemu_mutex_unlock(&pool_lock); + + qemu_coroutine_delete(co); +} + +static void __attribute__((constructor)) coroutine_pool_init(void) +{ + qemu_mutex_init(&pool_lock); +} + +static void __attribute__((destructor)) coroutine_pool_cleanup(void) +{ + Coroutine *co; + Coroutine *tmp; + + QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) { + QSLIST_REMOVE_HEAD(&pool, pool_next); + qemu_coroutine_delete(co); + } + + qemu_mutex_destroy(&pool_lock); +} + +static void coroutine_swap(Coroutine *from, Coroutine *to) +{ + CoroutineAction ret; + + ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD); + + qemu_co_queue_run_restart(to); + + switch (ret) { + case COROUTINE_YIELD: + return; + case COROUTINE_TERMINATE: + trace_qemu_coroutine_terminate(to); + coroutine_delete(to); + return; + default: + abort(); + } +} + +void qemu_coroutine_enter(Coroutine *co, void *opaque) +{ + Coroutine *self = qemu_coroutine_self(); + + trace_qemu_coroutine_enter(self, co, opaque); + + if (co->caller) { + fprintf(stderr, "Co-routine re-entered recursively\n"); + abort(); + } + + co->caller = self; + co->entry_arg = opaque; + coroutine_swap(self, co); +} + +void coroutine_fn qemu_coroutine_yield(void) +{ + Coroutine *self = qemu_coroutine_self(); + Coroutine *to = self->caller; + + trace_qemu_coroutine_yield(self, to); + + if (!to) { + fprintf(stderr, "Co-routine is yielding to no one\n"); + abort(); + } + + self->caller = NULL; + coroutine_swap(self, to); +} |