core: Global timer-wheel

Instantiate a process wide global instance of the timer wheel
data structure. Spawning glusterfs* process with option arg
"--global-timer-wheel" instantiates a global instance of
timer-wheel under global context (->ctx).

Translators can make use of this process wide instance [via a
call to glusterfs_global_timer_wheel()] instead of maintaining
an instance of their own and possibly consuming more memory.
Linux kernel too has a single instance of timer wheel where
subsystems such as IO, networking, etc.. make use of.

Bitrot daemon would be early consumers of this: bitrot translator
instances for multiple volumes would track objects belonging to
their respective bricks in this global expiry tracking data
structure. This is also a first step to move GlusterFS timer
mechanism to use timer-wheel.

Change-Id: Ie882df607e07acaced846ea269ebf1ece306d6ae
BUG: 1170075
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/10380
Tested-by: NetBSD Build System
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/libglusterfs/src/glusterfs.h b/libglusterfs/src/glusterfs.h
index 50a5dba86ee..e9b54535e66 100644
--- a/libglusterfs/src/glusterfs.h
+++ b/libglusterfs/src/glusterfs.h
@@ -434,6 +434,10 @@ struct _cmd_args {
         int              gid_timeout;
         char             gid_timeout_set;
         int              aux_gfid_mount;
+
+        /* need a process wide timer-wheel? */
+        int              global_timer_wheel;
+
         struct list_head xlator_options;  /* list of xlator_option_t */
 
 	/* fuse options */
@@ -496,6 +500,8 @@ typedef enum {
         MGMT_SSL_ALWAYS
 } mgmt_ssl_t;
 
+struct tvec_base;
+
 struct _glusterfs_ctx {
         cmd_args_t          cmd_args;
         char               *process_uuid;
@@ -570,6 +576,8 @@ struct _glusterfs_ctx {
         pthread_cond_t notify_cond;
         int notifying;
 
+        struct tvec_base *timer_wheel; /* global timer-wheel instance */
+
 };
 typedef struct _glusterfs_ctx glusterfs_ctx_t;