From c7196d16e8e03bb2a64be164d15a7502300eae0e Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Date: Wed, 20 Jul 2011 11:27:05 +1000
Subject: [PATCH] ReadOnly records: Add a new RPC function FETCH_WITH_HEADER.
 This function differs from the old FETCH in that this function will also
 fetch the record header and not just the record data

---
 client/ctdb_client.c      | 23 +++++++++++++++++++++++
 include/ctdb_protocol.h   |  6 ++++--
 server/ctdb_ltdb_server.c | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/client/ctdb_client.c b/client/ctdb_client.c
index 55c32735..d5c2f559 100644
--- a/client/ctdb_client.c
+++ b/client/ctdb_client.c
@@ -89,6 +89,7 @@ int ctdb_call_local(struct ctdb_db_context *ctdb_db, struct ctdb_call *call,
 	c->new_data = NULL;
 	c->reply_data = NULL;
 	c->status = 0;
+	c->header = header;
 
 	for (fn=ctdb_db->calls;fn;fn=fn->next) {
 		if (fn->id == call->call_id) break;
@@ -1693,6 +1694,27 @@ static int ctdb_fetch_func(struct ctdb_call_info *call)
 	return 0;
 }
 
+/*
+  this is a plain fetch procedure that all databases support
+  this returns the full record including the ltdb header
+*/
+static int ctdb_fetch_with_header_func(struct ctdb_call_info *call)
+{
+	call->reply_data = talloc(call, TDB_DATA);
+	if (call->reply_data == NULL) {
+		return -1;
+	}
+	call->reply_data->dsize = sizeof(struct ctdb_ltdb_header) + call->record_data.dsize;
+	call->reply_data->dptr  = talloc_size(call->reply_data, call->reply_data->dsize);
+	if (call->reply_data->dptr == NULL) {
+		return -1;
+	}
+	memcpy(call->reply_data->dptr, call->header, sizeof(struct ctdb_ltdb_header));
+	memcpy(&call->reply_data->dptr[sizeof(struct ctdb_ltdb_header)], call->record_data.dptr, call->record_data.dsize);
+
+	return 0;
+}
+
 /*
   attach to a specific database - client call
 */
@@ -1758,6 +1780,7 @@ struct ctdb_db_context *ctdb_attach(struct ctdb_context *ctdb, const char *name,
 	/* add well known functions */
 	ctdb_set_call(ctdb_db, ctdb_null_func, CTDB_NULL_FUNC);
 	ctdb_set_call(ctdb_db, ctdb_fetch_func, CTDB_FETCH_FUNC);
+	ctdb_set_call(ctdb_db, ctdb_fetch_with_header_func, CTDB_FETCH_WITH_HEADER_FUNC);
 
 	return ctdb_db;
 }
diff --git a/include/ctdb_protocol.h b/include/ctdb_protocol.h
index 0422afeb..b805182b 100644
--- a/include/ctdb_protocol.h
+++ b/include/ctdb_protocol.h
@@ -30,8 +30,9 @@
 #define CTDB_DS_ALIGNMENT 8
 
 
-#define CTDB_NULL_FUNC      0xFF000001
-#define CTDB_FETCH_FUNC     0xFF000002
+#define CTDB_NULL_FUNC                  0xFF000001
+#define CTDB_FETCH_FUNC                 0xFF000002
+#define CTDB_FETCH_WITH_HEADER_FUNC     0xFF000003
 
 
 struct ctdb_call {
@@ -50,6 +51,7 @@ struct ctdb_call {
 */
 struct ctdb_call_info {
 	TDB_DATA key;          /* record key */
+	struct ctdb_ltdb_header *header;
 	TDB_DATA record_data;  /* current data in the record */
 	TDB_DATA *new_data;    /* optionally updated record data */
 	TDB_DATA *call_data;   /* optionally passed from caller */
diff --git a/server/ctdb_ltdb_server.c b/server/ctdb_ltdb_server.c
index a93e2fa0..f04b7de4 100644
--- a/server/ctdb_ltdb_server.c
+++ b/server/ctdb_ltdb_server.c
@@ -49,6 +49,27 @@ static int ctdb_fetch_func(struct ctdb_call_info *call)
 	return 0;
 }
 
+/*
+  this is a plain fetch procedure that all databases support
+  this returns the full record including the ltdb header
+*/
+static int ctdb_fetch_with_header_func(struct ctdb_call_info *call)
+{
+	call->reply_data = talloc(call, TDB_DATA);
+	if (call->reply_data == NULL) {
+		return -1;
+	}
+	call->reply_data->dsize = sizeof(struct ctdb_ltdb_header) + call->record_data.dsize;
+	call->reply_data->dptr  = talloc_size(call->reply_data, call->reply_data->dsize);
+	if (call->reply_data->dptr == NULL) {
+		return -1;
+	}
+	memcpy(call->reply_data->dptr, call->header, sizeof(struct ctdb_ltdb_header));
+	memcpy(&call->reply_data->dptr[sizeof(struct ctdb_ltdb_header)], call->record_data.dptr, call->record_data.dsize);
+
+	return 0;
+}
+
 
 /**
  * write a record to a normal database
@@ -932,6 +953,17 @@ again:
 		return -1;
 	}
 
+	/* 
+	   all databases support the "fetch_with_header" function. we need this
+	   for efficient readonly record fetches
+	*/
+	ret = ctdb_daemon_set_call(ctdb, ctdb_db->db_id, ctdb_fetch_with_header_func, CTDB_FETCH_WITH_HEADER_FUNC);
+	if (ret != 0) {
+		DEBUG(DEBUG_CRIT,("Failed to setup fetch function for '%s'\n", ctdb_db->db_name));
+		talloc_free(ctdb_db);
+		return -1;
+	}
+
 	ret = ctdb_vacuum_init(ctdb_db);
 	if (ret != 0) {
 		DEBUG(DEBUG_CRIT,("Failed to setup vacuuming for "
-- 
2.34.1