Rename shm_handle to lttng_ust_shm_handle

[ust.git] / libringbuffer / frontend_internal.h

diff --git a/libringbuffer/frontend_internal.h b/libringbuffer/frontend_internal.h
index 02cb4d4a75d37c4b70f1f515be7fe5a1e18443d9..4c72318c2cf8bdab3a4ab03fd02399a82587d608 100644 (file)
--- a/libringbuffer/frontend_internal.h
+++ b/libringbuffer/frontend_internal.h
@@ -145,7 +145,7 @@ int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx);
 extern
 void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf,
                                 enum switch_mode mode,
-                                struct shm_handle *handle);
+                                struct lttng_ust_shm_handle *handle);
 
 /* Buffer write helpers */
 
@@ -182,7 +182,7 @@ void lib_ring_buffer_vmcore_check_deliver(const struct lib_ring_buffer_config *c
                                          struct lib_ring_buffer *buf,
                                          unsigned long commit_count,
                                          unsigned long idx,
-                                         struct shm_handle *handle)
+                                         struct lttng_ust_shm_handle *handle)
 {
        if (config->oops == RING_BUFFER_OOPS_CONSISTENCY)
                v_set(config, &shmp_index(handle, buf->commit_hot, idx)->seq, commit_count);
@@ -192,7 +192,7 @@ static inline
 int lib_ring_buffer_poll_deliver(const struct lib_ring_buffer_config *config,
                                 struct lib_ring_buffer *buf,
                                 struct channel *chan,
-                                struct shm_handle *handle)
+                                struct lttng_ust_shm_handle *handle)
 {
        unsigned long consumed_old, consumed_idx, commit_count, write_offset;
 
@@ -243,7 +243,7 @@ static inline
 unsigned long lib_ring_buffer_get_data_size(const struct lib_ring_buffer_config *config,
                                            struct lib_ring_buffer *buf,
                                            unsigned long idx,
-                                           struct shm_handle *handle)
+                                           struct lttng_ust_shm_handle *handle)
 {
        return subbuffer_get_data_size(config, &buf->backend, idx, handle);
 }
@@ -257,7 +257,7 @@ static inline
 int lib_ring_buffer_reserve_committed(const struct lib_ring_buffer_config *config,
                                      struct lib_ring_buffer *buf,
                                      struct channel *chan,
-                                     struct shm_handle *handle)
+                                     struct lttng_ust_shm_handle *handle)
 {
        unsigned long offset, idx, commit_count;
 
@@ -289,7 +289,7 @@ void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
                                   unsigned long offset,
                                   unsigned long commit_count,
                                   unsigned long idx,
-                                  struct shm_handle *handle)
+                                  struct lttng_ust_shm_handle *handle)
 {
        unsigned long old_commit_count = commit_count
                                         - chan->backend.subbuf_size;
@@ -376,7 +376,8 @@ void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
                         * RING_BUFFER_WAKEUP_BY_WRITER wakeup is not lock-free.
                         */
                        if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER
-                           && uatomic_read(&buf->active_readers)
+                           && (uatomic_read(&buf->active_readers)
+                               || uatomic_read(&buf->active_shadow_readers))
                            && lib_ring_buffer_poll_deliver(config, buf, chan, handle)) {
                                int wakeup_fd = shm_get_wakeup_fd(handle, &buf->self._ref);
 
@@ -386,6 +387,20 @@ void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
                                         * Wake-up the other end by
                                         * writing a null byte in the
                                         * pipe (non-blocking).
+                                        * Important note: Because
+                                        * writing into the pipe is
+                                        * non-blocking (and therefore
+                                        * we allow dropping wakeup
+                                        * data, as long as there is
+                                        * wakeup data present in the
+                                        * pipe buffer to wake up the
+                                        * consumer), the consumer
+                                        * should perform the following
+                                        * sequence for waiting:
+                                        * 1) empty the pipe (reads).
+                                        * 2) check if there is data in
+                                        *    the buffer.
+                                        * 3) wait on the pipe (poll).
                                         */
                                        do {
                                                ret = write(wakeup_fd, "", 1);
@@ -413,7 +428,7 @@ void lib_ring_buffer_write_commit_counter(const struct lib_ring_buffer_config *c
                                          unsigned long buf_offset,
                                          unsigned long commit_count,
                                          size_t slot_size,
-                                         struct shm_handle *handle)
+                                         struct lttng_ust_shm_handle *handle)
 {
        unsigned long offset, commit_seq_old;
 
@@ -439,10 +454,10 @@ void lib_ring_buffer_write_commit_counter(const struct lib_ring_buffer_config *c
 
 extern int lib_ring_buffer_create(struct lib_ring_buffer *buf,
                                  struct channel_backend *chanb, int cpu,
-                                 struct shm_handle *handle,
+                                 struct lttng_ust_shm_handle *handle,
                                  struct shm_object *shmobj);
 extern void lib_ring_buffer_free(struct lib_ring_buffer *buf,
-                                struct shm_handle *handle);
+                                struct lttng_ust_shm_handle *handle);
 
 /* Keep track of trap nesting inside ring buffer code */
 extern __thread unsigned int lib_ring_buffer_nesting;