The implementation cycles through the remotes in random order. This allows
clients to perform some load balancing across alternative implementations
of a service.
Signed-off-by: Ben Pfaff <b...@ovn.org>
---
lib/jsonrpc.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
lib/jsonrpc.h | 5 ++++-
2 files changed, 65 insertions(+), 6 deletions(-)
diff --git a/lib/jsonrpc.c b/lib/jsonrpc.c
index 2fae057de181..838334daa9a8 100644
--- a/lib/jsonrpc.c
+++ b/lib/jsonrpc.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 Nicira, Inc.
+ * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Nicira,
Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@
#include "openvswitch/ofpbuf.h"
#include "ovs-thread.h"
#include "poll-loop.h"
+#include "random.h"
#include "reconnect.h"
#include "stream.h"
#include "timeval.h"
@@ -753,6 +754,10 @@ jsonrpc_msg_to_json(struct jsonrpc_msg *m)
/* A JSON-RPC session with reconnection. */
struct jsonrpc_session {
+ char **remotes;
+ size_t n_remotes;
+ size_t next_remote;
+
struct reconnect *reconnect;
struct jsonrpc *rpc;
struct stream *stream;
@@ -762,6 +767,13 @@ struct jsonrpc_session {
uint8_t dscp;
};
+static void
+jsonrpc_session_pick_remote(struct jsonrpc_session *s)
+{
+ reconnect_set_name(s->reconnect,
+ s->remotes[s->next_remote++ % s->n_remotes]);
+}
+
/* Creates and returns a jsonrpc_session to 'name', which should be a string
* acceptable to stream_open() or pstream_open().
*
@@ -779,12 +791,36 @@ struct jsonrpc_session {
struct jsonrpc_session *
jsonrpc_session_open(const char *name, bool retry)
{
+ return jsonrpc_session_open_multiple(&name, 1, retry);
+}
+
+struct jsonrpc_session *
+jsonrpc_session_open_multiple(const char **names, size_t n, bool retry)
+{
struct jsonrpc_session *s;
s = xmalloc(sizeof *s);
+
+ /* Set 'n' remotes from 'names', shuffling them into random order. */
+ ovs_assert(n > 0);
+ s->remotes = xmalloc(n * sizeof *s->remotes);
+ for (size_t i = 0; i < n; i++) {
+ s->remotes[i] = xstrdup(names[i]);
+ }
+ s->n_remotes = n;
+ for (size_t i = 0; i < n; i++) {
+ size_t j = i + random_range(n - i);
+ char **r = s->remotes;
+ char *tmp = r[i];
+ r[i] = r[j];
+ r[j] = tmp;
+ }
+ s->next_remote = 0;
+
s->reconnect = reconnect_create(time_msec());
- reconnect_set_name(s->reconnect, name);
+ jsonrpc_session_pick_remote(s);
reconnect_enable(s->reconnect, time_msec());
+ reconnect_set_backoff_free_tries(s->reconnect, n);
s->rpc = NULL;
s->stream = NULL;
s->pstream = NULL;
@@ -792,10 +828,11 @@ jsonrpc_session_open(const char *name, bool retry)
s->dscp = 0;
s->last_error = 0;
+ const char *name = reconnect_get_name(s->reconnect);
if (!pstream_verify_name(name)) {
reconnect_set_passive(s->reconnect, true, time_msec());
} else if (!retry) {
- reconnect_set_max_tries(s->reconnect, 1);
+ reconnect_set_max_tries(s->reconnect, n);
reconnect_set_backoff(s->reconnect, INT_MAX, INT_MAX);
}
@@ -817,6 +854,10 @@ jsonrpc_session_open_unreliably(struct jsonrpc *jsonrpc,
uint8_t dscp)
struct jsonrpc_session *s;
s = xmalloc(sizeof *s);
+ s->remotes = xmalloc(sizeof *s->remotes);
+ s->remotes[0] = xstrdup(jsonrpc_get_name(jsonrpc));
+ s->n_remotes = 1;
+ s->next_remote = 0;
s->reconnect = reconnect_create(time_msec());
reconnect_set_quiet(s->reconnect, true);
reconnect_set_name(s->reconnect, jsonrpc_get_name(jsonrpc));
@@ -839,6 +880,10 @@ jsonrpc_session_close(struct jsonrpc_session *s)
reconnect_destroy(s->reconnect);
stream_close(s->stream);
pstream_close(s->pstream);
+ for (size_t i = 0; i < s->n_remotes; i++) {
+ free(s->remotes[i]);
+ }
+ free(s->remotes);
free(s);
}
}
@@ -850,12 +895,15 @@ jsonrpc_session_disconnect(struct jsonrpc_session *s)
jsonrpc_error(s->rpc, EOF);
jsonrpc_close(s->rpc);
s->rpc = NULL;
- s->seqno++;
} else if (s->stream) {
stream_close(s->stream);
s->stream = NULL;
- s->seqno++;
+ } else {
+ return;
}
+
+ s->seqno++;
+ jsonrpc_session_pick_remote(s);
}
static void
@@ -882,6 +930,7 @@ jsonrpc_session_connect(struct jsonrpc_session *s)
if (error) {
reconnect_connect_failed(s->reconnect, time_msec(), error);
+ jsonrpc_session_pick_remote(s);
}
s->seqno++;
}
@@ -945,6 +994,7 @@ jsonrpc_session_run(struct jsonrpc_session *s)
s->stream = NULL;
} else if (error != EAGAIN) {
reconnect_connect_failed(s->reconnect, time_msec(), error);
+ jsonrpc_session_pick_remote(s);
stream_close(s->stream);
s->stream = NULL;
s->last_error = error;
@@ -1015,6 +1065,12 @@ jsonrpc_session_get_id(const struct jsonrpc_session *s)
}
}
+size_t
+jsonrpc_session_get_n_remotes(const struct jsonrpc_session *s)
+{
+ return s->n_remotes;
+}
+
/* Always takes ownership of 'msg', regardless of success. */
int
jsonrpc_session_send(struct jsonrpc_session *s, struct jsonrpc_msg *msg)
diff --git a/lib/jsonrpc.h b/lib/jsonrpc.h
index 9b4fb0e51374..97110c00ff05 100644
--- a/lib/jsonrpc.h
+++ b/lib/jsonrpc.h
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2009, 2010, 2012, 2013 Nicira, Inc.
+ * Copyright (c) 2009, 2010, 2012, 2013, 2017 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -99,6 +99,8 @@ struct json *jsonrpc_msg_to_json(struct jsonrpc_msg *);
/* A JSON-RPC session with reconnection. */
struct jsonrpc_session *jsonrpc_session_open(const char *name, bool retry);
+struct jsonrpc_session *jsonrpc_session_open_multiple(const char **remotes,
+ size_t n, bool retry);
struct jsonrpc_session *jsonrpc_session_open_unreliably(struct jsonrpc *,
uint8_t);
void jsonrpc_session_close(struct jsonrpc_session *);
@@ -108,6 +110,7 @@ void jsonrpc_session_wait(struct jsonrpc_session *);
size_t jsonrpc_session_get_backlog(const struct jsonrpc_session *);
const char *jsonrpc_session_get_name(const struct jsonrpc_session *);
+size_t jsonrpc_session_get_n_remotes(const struct jsonrpc_session *);
int jsonrpc_session_send(struct jsonrpc_session *, struct jsonrpc_msg *);
struct jsonrpc_msg *jsonrpc_session_recv(struct jsonrpc_session *);
--
2.10.2
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