include/babeltrace/context.h

   1 #ifndef _BABELTRACE_CONTEXT_H
   2 #define _BABELTRACE_CONTEXT_H
   3
   4 /*
   5  * BabelTrace
   6  *
   7  * context header
   8  *
   9  * Copyright 2012 EfficiOS Inc. and Linux Foundation
  10  *
  11  * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  12  *         Julien Desfossez <julien.desfossez@efficios.com>
  13  *
  14  * Permission is hereby granted, free of charge, to any person obtaining
  15  * a copy of this software and associated documentation files (the
  16  * "Software"), to deal in the Software without restriction, including
  17  * without limitation the rights to use, copy, modify, merge, publish,
  18  * distribute, sublicense, and/or sell copies of the Software, and to
  19  * permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be
  23  * included in all copies or substantial portions of the Software.
  24  */
  25
  26 struct trace_collection;
  27 struct GHashTable;
  28
  29 /*
  30  * The context represents the object in which a trace_collection is
  31  * open. As long as this structure is allocated, the trace_collection is
  32  * open and the traces it contains can be read and seeked by the
  33  * iterators and callbacks.
  34  *
  35  * It has to be created with the bt_context_create() function and
  36  * destroyed by calling one more bt_context_put() than bt_context_get()
  37  */
  38 struct bt_context {
  39         struct trace_collection *tc;
  40         GHashTable *trace_handles;
  41         int refcount;
  42         int last_trace_handle_id;
  43 };
  44
  45 /*
  46  * bt_context_create : create a Babeltrace context
  47  *
  48  * Allocate a new context. The creation of the context sets the refcount
  49  * to 1.
  50  *
  51  * Returns an allocated context on success and NULL on error
  52  */
  53 struct bt_context *bt_context_create(void);
  54
  55 /*
  56  * bt_context_add_trace : Add a trace by path to the context
  57  *
  58  * Open a trace
  59  *
  60  * Return the trace handle id of the opened trace
  61  */
  62 int bt_context_add_trace(struct bt_context *ctx, const char *path,
  63                 const char *format);
  64
  65 /*
  66  * bt_context_add_traces: Open a trace recursively
  67  *
  68  * Find each trace present in the subdirectory starting from the given
  69  * path, and add them to the context.
  70  *
  71  * Return: 0 on success, nonzero on failure.
  72  */
  73 int bt_context_add_traces(struct bt_context *ctx, const char *path,
  74                 const char *format);
  75
  76 /*
  77  * bt_context_remove_trace: Remove a trace from the context.
  78  *
  79  * Effectively closing the trace.
  80  */
  81 void bt_context_remove_trace(struct bt_context *ctx, int trace_id);
  82
  83 /*
  84  * bt_context_get and bt_context_put : increments and decrement the
  85  * refcount of the context
  86  *
  87  * These functions ensures that the context won't be destroyed when it
  88  * is in use. The same number of get and put (plus one extra put to
  89  * release the initial reference done at creation) has to be done to
  90  * destroy a context.
  91  *
  92  * When the context refcount is decremented to 0 by a bt_context_put,
  93  * the context is freed.
  94  */
  95 void bt_context_get(struct bt_context *ctx);
  96 void bt_context_put(struct bt_context *ctx);
  97
  98 #endif /* _BABELTRACE_CONTEXT_H */