Implement file-backed ring buffer

[lttng-ust.git] / libringbuffer / shm.h

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index 8987f72a30f3dc234cf2ca9d7b777c86b6197cf3..9253e952dea720de230b894a81e77660f377e5bc 100644 (file)
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -26,6 +26,20 @@
 #include <urcu/compiler.h>
 #include "shm_types.h"
 
+/* channel_handle_create - for UST. */
+extern
+struct lttng_ust_shm_handle *channel_handle_create(void *data,
+                               uint64_t memory_map_size, int wakeup_fd);
+/* channel_handle_add_stream - for UST. */
+extern
+int channel_handle_add_stream(struct lttng_ust_shm_handle *handle,
+               int shm_fd, int wakeup_fd, uint32_t stream_nr,
+               uint64_t memory_map_size);
+unsigned int channel_handle_get_nr_streams(struct lttng_ust_shm_handle *handle);
+extern
+void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
+               int consumer);
+
 /*
  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  * both the index and offset with known boundaries.
@@ -72,11 +86,17 @@ void _set_shmp(struct shm_ref *ref, struct shm_ref src)
 #define set_shmp(ref, src)     _set_shmp(&(ref)._ref, src)
 
 struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
-struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
-                       int shm_fd, int wait_fd, size_t memory_map_size);
+struct shm_object *shm_object_table_alloc(struct shm_object_table *table,
+                       size_t memory_map_size,
+                       enum shm_object_type type,
+                       const char *shm_path);
+struct shm_object *shm_object_table_append_shm(struct shm_object_table *table,
+                       int shm_fd, int wakeup_fd, uint32_t stream_nr,
+                       size_t memory_map_size);
+/* mem ownership is passed to shm_object_table_append_mem(). */
+struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
+                       void *mem, size_t memory_map_size, int wakeup_fd);
 void shm_object_table_destroy(struct shm_object_table *table);
-struct shm_object *shm_object_table_append(struct shm_object_table *table,
-                                          size_t memory_map_size);
 
 /*
  * zalloc_shm - allocate memory within a shm object.
@@ -88,6 +108,20 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
 void align_shm(struct shm_object *obj, size_t align);
 
+static inline
+int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
+{
+       struct shm_object_table *table = handle->table;
+       struct shm_object *obj;
+       size_t index;
+
+       index = (size_t) ref->index;
+       if (caa_unlikely(index >= table->allocated_len))
+               return -EPERM;
+       obj = &table->objects[index];
+       return obj->wait_fd[0];
+}
+
 static inline
 int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 {
@@ -100,26 +134,78 @@ int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
                return -EPERM;
        obj = &table->objects[index];
        return obj->wait_fd[1];
+}
+
+static inline
+int shm_close_wait_fd(struct lttng_ust_shm_handle *handle,
+               struct shm_ref *ref)
+{
+       struct shm_object_table *table = handle->table;
+       struct shm_object *obj;
+       int wait_fd;
+       size_t index;
+       int ret;
 
+       index = (size_t) ref->index;
+       if (caa_unlikely(index >= table->allocated_len))
+               return -EPERM;
+       obj = &table->objects[index];
+       wait_fd = obj->wait_fd[0];
+       if (wait_fd < 0)
+               return -ENOENT;
+       obj->wait_fd[0] = -1;
+       ret = close(wait_fd);
+       if (ret) {
+               ret = -errno;
+               return ret;
+       }
+       return 0;
 }
 
 static inline
-int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
+int shm_close_wakeup_fd(struct lttng_ust_shm_handle *handle,
+               struct shm_ref *ref)
 {
        struct shm_object_table *table = handle->table;
        struct shm_object *obj;
+       int wakeup_fd;
        size_t index;
+       int ret;
 
        index = (size_t) ref->index;
        if (caa_unlikely(index >= table->allocated_len))
                return -EPERM;
        obj = &table->objects[index];
-       return obj->wait_fd[0];
+       wakeup_fd = obj->wait_fd[1];
+       if (wakeup_fd < 0)
+               return -ENOENT;
+       obj->wait_fd[1] = -1;
+       ret = close(wakeup_fd);
+       if (ret) {
+               ret = -errno;
+               return ret;
+       }
+       return 0;
 }
 
 static inline
-int shm_get_object_data(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
-               int **shm_fd, int **wait_fd, uint64_t **memory_map_size)
+int shm_get_shm_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
+{
+       struct shm_object_table *table = handle->table;
+       struct shm_object *obj;
+       size_t index;
+
+       index = (size_t) ref->index;
+       if (caa_unlikely(index >= table->allocated_len))
+               return -EPERM;
+       obj = &table->objects[index];
+       return obj->shm_fd;
+}
+
+
+static inline
+int shm_get_shm_size(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
+               uint64_t *size)
 {
        struct shm_object_table *table = handle->table;
        struct shm_object *obj;
@@ -129,9 +215,7 @@ int shm_get_object_data(struct lttng_ust_shm_handle *handle, struct shm_ref *ref
        if (caa_unlikely(index >= table->allocated_len))
                return -EPERM;
        obj = &table->objects[index];
-       *shm_fd = &obj->shm_fd;
-       *wait_fd = &obj->wait_fd[0];
-       *memory_map_size = &obj->allocated_len;
+       *size = obj->memory_map_size;
        return 0;
 }