src/bin/lttng-relayd/tracefile-array.h

   1 #ifndef _TRACEFILE_ARRAY_H
   2 #define _TRACEFILE_ARRAY_H
   3
   4 /*
   5  * Copyright (C) 2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License, version 2 only, as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along with
  17  * this program; if not, write to the Free Software Foundation, Inc., 51
  18  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include <limits.h>
  22 #include <inttypes.h>
  23 #include <pthread.h>
  24 #include <stdbool.h>
  25
  26 struct tracefile {
  27         /* Per-tracefile head/tail seq. */
  28         uint64_t seq_head;      /* Newest seqcount. Inclusive. */
  29         uint64_t seq_tail;      /* Oldest seqcount. Inclusive. */
  30 };
  31
  32 enum tracefile_rotate_type {
  33         TRACEFILE_ROTATE_READ,
  34         TRACEFILE_ROTATE_WRITE,
  35 };
  36
  37 /*
  38  * Represents an array of trace files in a stream.
  39  * head is the most recent file/trace packet.
  40  * tail is the oldest file/trace packet.
  41  *
  42  * There are two heads: a "read" head and a "write" head. The "write" head is
  43  * the position of the newest data file. The "read" head position is only moved
  44  * forward when the index is received.
  45  *
  46  * The viewer uses the "read" head position as upper bound, which
  47  * ensures it never attempts to open a non-existing index file.
  48  */
  49 struct tracefile_array {
  50         struct tracefile *tf;
  51         size_t count;
  52
  53         /* Current head/tail files. */
  54         uint64_t file_head_read;
  55         uint64_t file_head_write;
  56         uint64_t file_tail;
  57
  58         /* Overall head/tail seq for the entire array. Inclusive. */
  59         uint64_t seq_head;
  60         uint64_t seq_tail;
  61 };
  62
  63 struct tracefile_array *tracefile_array_create(size_t count);
  64 void tracefile_array_destroy(struct tracefile_array *tfa);
  65
  66 void tracefile_array_file_rotate(struct tracefile_array *tfa, enum tracefile_rotate_type type);
  67 void tracefile_array_commit_seq(struct tracefile_array *tfa,
  68                 uint64_t new_seq_head);
  69 void tracefile_array_reset(struct tracefile_array *tfa);
  70
  71 uint64_t tracefile_array_get_read_file_index_head(struct tracefile_array *tfa);
  72 /* May return -1ULL in the case where we have not received any indexes yet. */
  73 uint64_t tracefile_array_get_seq_head(struct tracefile_array *tfa);
  74
  75 uint64_t tracefile_array_get_file_index_tail(struct tracefile_array *tfa);
  76 /* May return -1ULL in the case where we have not received any indexes yet. */
  77 uint64_t tracefile_array_get_seq_tail(struct tracefile_array *tfa);
  78
  79 bool tracefile_array_seq_in_file(struct tracefile_array *tfa,
  80                 uint64_t file_index, uint64_t seq);
  81
  82 #endif /* _STREAM_H */