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#ifndef _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
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#define _LTTNG_RING_BUFFER_FRONTEND_TYPES_H
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* libringbuffer/frontend_types.h
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* Ring Buffer Library Synchronization Header (types).
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* Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; only
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* version 2.1 of the License.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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* See ring_buffer_frontend.c for more information on wait-free algorithms.
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#include <urcu/list.h>
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#include <urcu/uatomic.h>
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#include <lttng/ringbuffer-config.h>
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#include <usterr-signal-safe.h>
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#include "backend_types.h"
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#include "shm_internal.h"
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* A switch is done during tracing or as a final flush after tracing (so it
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* won't write in the new sub-buffer).
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enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
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/* channel: collection of per-cpu ring buffers. */
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unsigned long commit_count_mask; /*
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* Commit count mask, removing
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* the MSBs corresponding to
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* bits used to represent the
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unsigned long switch_timer_interval; /* Buffer flush (jiffies) */
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unsigned long read_timer_interval; /* Reader wakeup (jiffies) */
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//wait_queue_head_t read_wait; /* reader wait queue */
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int finalized; /* Has channel been finalized */
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size_t priv_data_offset;
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/* Note: padding field is missing */
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* Associated backend contains a variable-length array. Needs to
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struct channel_backend backend; /* Associated backend */
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} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
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/* Per-subbuffer commit counters used on the hot path */
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#define RB_COMMIT_COUNT_HOT_PADDING 16
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struct commit_counters_hot {
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union v_atomic cc; /* Commit counter */
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union v_atomic seq; /* Consecutive commits */
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char padding[RB_COMMIT_COUNT_HOT_PADDING];
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} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
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/* Per-subbuffer commit counters used only on cold paths */
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#define RB_COMMIT_COUNT_COLD_PADDING 24
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struct commit_counters_cold {
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union v_atomic cc_sb; /* Incremented _once_ at sb switch */
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char padding[RB_COMMIT_COUNT_COLD_PADDING];
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} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
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/* ring buffer state */
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#define RB_RING_BUFFER_PADDING 64
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struct lttng_ust_lib_ring_buffer {
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/* First 32 bytes cache-hot cacheline */
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union v_atomic offset; /* Current offset in the buffer */
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DECLARE_SHMP(struct commit_counters_hot, commit_hot);
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/* Commit count per sub-buffer */
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* Current offset in the buffer
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* standard atomic access (shared)
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/* End of first 32 bytes cacheline */
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union v_atomic last_tsc; /*
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* Last timestamp written in the buffer.
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struct lttng_ust_lib_ring_buffer_backend backend; /* Associated backend */
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DECLARE_SHMP(struct commit_counters_cold, commit_cold);
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/* Commit count per sub-buffer */
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long active_readers; /*
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* Active readers count
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* standard atomic access (shared)
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long active_shadow_readers;
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/* Dropped records */
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union v_atomic records_lost_full; /* Buffer full */
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union v_atomic records_lost_wrap; /* Nested wrap-around */
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union v_atomic records_lost_big; /* Events too big */
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union v_atomic records_count; /* Number of records written */
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union v_atomic records_overrun; /* Number of overwritten records */
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//wait_queue_head_t read_wait; /* reader buffer-level wait queue */
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int finalized; /* buffer has been finalized */
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//struct timer_list switch_timer; /* timer for periodical switch */
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//struct timer_list read_timer; /* timer for read poll */
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unsigned long get_subbuf_consumed; /* Read-side consumed */
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unsigned long prod_snapshot; /* Producer count snapshot */
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unsigned long cons_snapshot; /* Consumer count snapshot */
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unsigned int get_subbuf:1, /* Sub-buffer being held by reader */
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switch_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */
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read_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */
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/* shmp pointer to self */
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DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, self);
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char padding[RB_RING_BUFFER_PADDING];
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} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
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void *channel_get_private(struct channel *chan)
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return ((char *) chan) + chan->priv_data_offset;
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#ifndef __rb_same_type
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#define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
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* Issue warnings and disable channels upon internal error.
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* Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend
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#define CHAN_WARN_ON(c, cond) \
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struct channel *__chan; \
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int _____ret = caa_unlikely(cond); \
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if (__rb_same_type(*(c), struct channel_backend)) \
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__chan = caa_container_of((void *) (c), \
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else if (__rb_same_type(*(c), struct channel)) \
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__chan = (void *) (c); \
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uatomic_inc(&__chan->record_disabled); \
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#endif /* _LTTNG_RING_BUFFER_FRONTEND_TYPES_H */
added
removed
libringbuffer/frontend_types.h
