--- /dev/null
+/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring Buffer Library Synchronization Header (API).
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ */
+
+#ifndef _LTTNG_RING_BUFFER_FRONTEND_H
+#define _LTTNG_RING_BUFFER_FRONTEND_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <urcu/compiler.h>
+#include <urcu/uatomic.h>
+
+#include "smp.h"
+
+/* Internal helpers */
+#include "frontend_internal.h"
+
+/* Buffer creation/removal and setup operations */
+
+/*
+ * switch_timer_interval is the time interval (in us) to fill sub-buffers with
+ * padding to let readers get those sub-buffers. Used for live streaming.
+ *
+ * read_timer_interval is the time interval (in us) to wake up pending readers.
+ *
+ * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
+ * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
+ * be set to NULL for other backends.
+ *
+ * private data is a memory area for configuration data. This memory is
+ * managed by lib ring buffer. priv_data_align is the alignment required
+ * for the private data area.
+ */
+
+extern
+struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buffer_config *config,
+ const char *name,
+ size_t priv_data_align,
+ size_t priv_data_size,
+ void *priv_data_init,
+ void *priv,
+ void *buf_addr,
+ size_t subbuf_size, size_t num_subbuf,
+ unsigned int switch_timer_interval,
+ unsigned int read_timer_interval,
+ const int *stream_fds, int nr_stream_fds,
+ int64_t blocking_timeout)
+ __attribute__((visibility("hidden")));
+
+/*
+ * channel_destroy finalizes all channel's buffers, waits for readers to
+ * release all references, and destroys the channel.
+ */
+void channel_destroy(struct lttng_ust_lib_ring_buffer_channel *chan,
+ struct lttng_ust_shm_handle *handle,
+ int consumer)
+ __attribute__((visibility("hidden")));
+
+
+/* Buffer read operations */
+
+/*
+ * Iteration on channel cpumask needs to issue a read barrier to match the write
+ * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
+ * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
+ * only performed at channel destruction.
+ */
+#define for_each_channel_cpu(cpu, chan) \
+ for_each_possible_cpu(cpu)
+
+extern struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_channel *chan, int cpu,
+ struct lttng_ust_shm_handle *handle,
+ int *shm_fd, int *wait_fd,
+ int *wakeup_fd,
+ uint64_t *memory_map_size)
+ __attribute__((visibility("hidden")));
+
+extern
+int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_channel *chan,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern
+int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_channel *chan,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern
+int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_channel *chan,
+ struct lttng_ust_shm_handle *handle,
+ int cpu)
+ __attribute__((visibility("hidden")));
+
+extern
+int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_channel *chan,
+ struct lttng_ust_shm_handle *handle,
+ int cpu)
+ __attribute__((visibility("hidden")));
+
+extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+/*
+ * Initialize signals for ring buffer. Should be called early e.g. by
+ * main() in the program to affect all threads.
+ */
+void lib_ringbuffer_signal_init(void)
+ __attribute__((visibility("hidden")));
+
+/*
+ * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
+ */
+extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf,
+ unsigned long *consumed,
+ unsigned long *produced,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern int lib_ring_buffer_snapshot_sample_positions(
+ struct lttng_ust_lib_ring_buffer *buf,
+ unsigned long *consumed,
+ unsigned long *produced,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf,
+ unsigned long consumed_new,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
+ unsigned long consumed,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+/*
+ * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
+ * to read sub-buffers sequentially.
+ */
+static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+{
+ int ret;
+
+ ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
+ &buf->prod_snapshot, handle);
+ if (ret)
+ return ret;
+ ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
+ return ret;
+}
+
+static inline
+void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+{
+ struct lttng_ust_lib_ring_buffer_channel *chan;
+
+ chan = shmp(handle, buf->backend.chan);
+ if (!chan)
+ return;
+ lib_ring_buffer_put_subbuf(buf, handle);
+ lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot, chan),
+ handle);
+}
+
+extern void channel_reset(struct lttng_ust_lib_ring_buffer_channel *chan)
+ __attribute__((visibility("hidden")));
+
+extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+ __attribute__((visibility("hidden")));
+
+static inline
+unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->offset);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_consumed(
+ const struct lttng_ust_lib_ring_buffer_config *config __attribute__((unused)),
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return uatomic_read(&buf->consumed);
+}
+
+/*
+ * Must call lib_ring_buffer_is_finalized before reading counters (memory
+ * ordering enforced with respect to trace teardown).
+ */
+static inline
+int lib_ring_buffer_is_finalized(
+ const struct lttng_ust_lib_ring_buffer_config *config __attribute__((unused)),
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ int finalized = CMM_ACCESS_ONCE(buf->finalized);
+ /*
+ * Read finalized before counters.
+ */
+ cmm_smp_rmb();
+ return finalized;
+}
+
+static inline
+int lib_ring_buffer_channel_is_finalized(const struct lttng_ust_lib_ring_buffer_channel *chan)
+{
+ return chan->finalized;
+}
+
+static inline
+int lib_ring_buffer_channel_is_disabled(const struct lttng_ust_lib_ring_buffer_channel *chan)
+{
+ return uatomic_read(&chan->record_disabled);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_read_data_size(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf,
+ struct lttng_ust_shm_handle *handle)
+{
+ return subbuffer_get_read_data_size(config, &buf->backend, handle);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_count(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_count);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_overrun(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_overrun);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_full(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_full);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_wrap(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_wrap);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_big(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_big);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_read(
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->backend.records_read);
+}
+
+#endif /* _LTTNG_RING_BUFFER_FRONTEND_H */
projects / lttng-ust.git / blobdiff