ctdb-common: Add request id abstraction

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>

2 files changed, 178 insertions, 0 deletions

diff --git a/ctdb/common/reqid.c b/ctdb/common/reqid.c
new file mode 100644
index 00000000000..0e651cfa530
--- /dev/null
+++ b/ctdb/common/reqid.c
@@ -0,0 +1,89 @@
+/*
+   ctdb request id handling code
+
+   Copyright (C) Amitay Isaacs  2015
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "replace.h"
+
+#include <talloc.h>
+
+#include "lib/util/idtree.h"
+#include "reqid.h"
+
+struct reqid_context {
+	struct idr_context *idr;
+	uint32_t lastid;
+};
+
+int reqid_init(TALLOC_CTX *mem_ctx, int start_id,
+	       struct reqid_context **result)
+{
+	struct reqid_context *reqid_ctx;
+
+	reqid_ctx = talloc_zero(mem_ctx, struct reqid_context);
+	if (reqid_ctx == NULL) {
+		return ENOMEM;
+	}
+
+	reqid_ctx->idr = idr_init(reqid_ctx);
+	if (reqid_ctx->idr == NULL) {
+		talloc_free(reqid_ctx);
+		return ENOMEM;
+	}
+
+	if (start_id <= 0) {
+		start_id = 1;
+	}
+	reqid_ctx->lastid = start_id;
+
+	*result = reqid_ctx;
+	return 0;
+}
+
+uint32_t reqid_new(struct reqid_context *reqid_ctx, void *private_data)
+{
+	int id;
+
+	id = idr_get_new_above(reqid_ctx->idr, private_data,
+			       reqid_ctx->lastid+1, INT_MAX);
+	if (id < 0) {
+		/* reqid wrapped */
+		id = idr_get_new(reqid_ctx->idr, private_data, INT_MAX);
+	}
+	if (id == -1) {
+		return REQID_INVALID;
+	}
+
+	reqid_ctx->lastid = id;
+	return id;
+}
+
+void *_reqid_find(struct reqid_context *reqid_ctx, uint32_t reqid)
+{
+	return idr_find(reqid_ctx->idr, reqid);
+}
+
+int reqid_remove(struct reqid_context *reqid_ctx, uint32_t reqid)
+{
+	int ret;
+
+	ret = idr_remove(reqid_ctx->idr, reqid);
+	if (ret < 0) {
+		return ENOENT;
+	}
+	return 0;
+}
diff --git a/ctdb/common/reqid.h b/ctdb/common/reqid.h
new file mode 100644
index 00000000000..736e5b38901
--- /dev/null
+++ b/ctdb/common/reqid.h
@@ -0,0 +1,89 @@
+/*
+   Request id database
+
+   Copyright (C) Amitay Isaacs  2015
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __CTDB_REQID_H__
+#define __CTDB_REQID_H__
+
+#include <talloc.h>
+
+/**
+ * @file reqid.h
+ *
+ * @brief Request id database
+ *
+ * CTDB tracks messsages using request id. CTDB stores client state for each
+ * request id to process the replies correctly.
+ */
+
+/**
+ * @brief Abstract struct to store request id database
+ */
+struct reqid_context;
+
+#define REQID_INVALID	0xffffffff
+
+/**
+ * @brief Initialize request id database
+ *
+ * This returns a new request id context. Freeing this context will free
+ * all the memory associated with request id database.
+ *
+ * @param[in] mem_ctx Talloc memory context
+ * @param[in] start_id The initial id
+ * @param[out] result The new talloc_context structure
+ * @return 0 on success, errno on failure
+ */
+int reqid_init(TALLOC_CTX *mem_ctx, int start_id,
+	       struct reqid_context **result);
+
+/**
+ * @brief Generate new request id and associate given data with the request id
+ *
+ * @param[in] reqid_ctx The request id context
+ * @param[in] private_data The state to associate with new request id
+ * @return new request id, REQID_INVALID on failure
+ */
+uint32_t reqid_new(struct reqid_context *reqid_ctx, void *private_data);
+
+#ifdef DOXYGEN
+/**
+ * @brief Fetch the data associated with the request id
+ *
+ * @param[in] reqid_ctx The request id context
+ * @param[in] reqid The request id
+ * @param[in] type The data type of the stored data
+ * @return the data stored for the reqid, NULL on failure
+ */
+type *reqid_find(struct reqid_context *reqid_ctx, uint32_t reqid, #type);
+#else
+void *_reqid_find(struct reqid_context *reqid_ctx, uint32_t reqid);
+#define reqid_find(ctx, reqid, type) \
+	(type *)talloc_check_name(_reqid_find(ctx, reqid), #type)
+#endif
+
+/**
+ * @brief Remove the data associated with the request id
+ *
+ * @param[in] reqid_ctx The request id context
+ * @param[in] reqid The request id
+ * @return 0 on success, errno on failure
+ */
+int reqid_remove(struct reqid_context *reqid_ctx, uint32_t reqid);
+
+#endif /* __CTDB_REQID_H__ */