Add missing context.h/context.c

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/include/babeltrace/context.h b/include/babeltrace/context.h
new file mode 100644 (file)
index 0000000..55fe231
--- /dev/null
+++ b/include/babeltrace/context.h
@@ -0,0 +1,76 @@
+#ifndef _BABELTRACE_CONTEXT_H
+#define _BABELTRACE_CONTEXT_H
+
+/*
+ * BabelTrace
+ *
+ * context header
+ *
+ * Copyright 2012 EfficiOS Inc. and Linux Foundation
+ *
+ * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *         Julien Desfossez <julien.desfossez@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ */
+
+struct trace_collection;
+
+/*
+ * The context represents the object in which a trace_collection is open. As
+ * long as this structure is allocated, the trace_collection is open and the
+ * traces it contains can be read and seeked by the iterators and callbacks.
+ *
+ * It has to be created with the bt_context_create() function and destroyed by
+ * bt_context_destroy()
+ */
+struct bt_context {
+       struct trace_collection *tc;
+       int refcount;
+};
+
+/*
+ * bt_context_create : create a Babeltrace context
+ *
+ * Allocate a new context and assign the trace_collection passed in
+ * parameter as the context trace_collection. The trace_collection
+ * must contain an array of valid trace_descriptors. The creation of
+ * the context sets the refcount to 1.
+ *
+ * Returns an allocated context on success and NULL on error
+ */
+struct bt_context *bt_context_create(struct trace_collection *tc);
+
+/*
+ * bt_context_destroy : destroy a context
+ *
+ * If the context is still in use (by an iterator or a callback), the
+ * destroy fails and returns -1, on success : return 0.
+ */
+int bt_context_destroy(struct bt_context *ctx);
+
+/*
+ * bt_context_get and bt_context_put : increments and decrement the refcount of
+ * the context
+ *
+ * These functions ensures that the context won't be destroyed when it is in
+ * use. The same number of get and put has to be done to be able to destroy a
+ * context.
+ *
+ * Return 0 on success, -1 if the context pointer is invalid.  When the context
+ * refcount is decremented to 0 by a bt_context_put, it calls
+ * bt_context_destroy to free the context. In this case the return code of
+ * bt_context_destroy is returned.
+ */
+int bt_context_get(struct bt_context *ctx);
+int bt_context_put(struct bt_context *ctx);
+
+#endif /* _BABELTRACE_CONTEXT_H */

diff --git a/lib/context.c b/lib/context.c
new file mode 100644 (file)
index 0000000..36efc9d
--- /dev/null
+++ b/lib/context.c
@@ -0,0 +1,76 @@
+/*
+ * context.c
+ *
+ * Babeltrace Library
+ *
+ * Copyright 2011-2012 EfficiOS Inc. and Linux Foundation
+ *
+ * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *         Julien Desfossez <julien.desfossez@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ */
+
+#include <babeltrace/babeltrace.h>
+#include <babeltrace/context.h>
+#include <stdlib.h>
+
+struct bt_context *bt_context_create(struct trace_collection *tc)
+{
+       struct bt_context *ctx;
+
+       ctx = calloc(1, sizeof(struct bt_context));
+       if (ctx == NULL) {
+               perror("allocating context");
+               goto error;
+       }
+
+       ctx->tc = tc;
+       ctx->refcount = 1;
+
+       return ctx;
+
+error:
+       return NULL;
+}
+
+int bt_context_destroy(struct bt_context *ctx)
+{
+       if (ctx) {
+               if (ctx->refcount >= 1)
+                       goto ctx_used;
+
+               free(ctx);
+       }
+       return 0;
+
+ctx_used:
+       return -1;
+}
+
+int bt_context_get(struct bt_context *ctx)
+{
+       if (!ctx)
+               return -1;
+       ctx->refcount++;
+       return 0;
+}
+
+int bt_context_put(struct bt_context *ctx)
+{
+       if (!ctx)
+               return -1;
+
+       ctx->refcount--;
+       if (ctx->refcount == 0)
+               return bt_context_destroy(ctx);
+       return 0;
+}