[Xen-API] [PATCH] add an explicit cache of the local hostname

[David Scott <dave.scott@xxxxxxxxxxxxx>]

# HG changeset patch
# User David Scott <dave.scott@xxxxxxxxxxxxx>
# Date 1271091282 -3600
# Node ID 06f4d30cef5f458c7b2cf8b47427424c9948db4f
# Parent  da78a9af0fdf61ad133a0c04d96d7eb286a94cdb
CA-40149: Add an explicit cache of the local hostname and make it posible to 
invalidate the cache.

The hostname is included in every log line.

Signed-off-by: David Scott <dave.scott@xxxxxxxxxxxxx>

diff -r da78a9af0fdf -r 06f4d30cef5f log/debug.ml
--- a/log/debug.ml      Fri Apr 09 10:49:50 2010 +0100
+++ b/log/debug.ml      Mon Apr 12 17:54:42 2010 +0100
@@ -21,11 +21,6 @@
 
 let get_thread_id () =
   try Thread.id (Thread.self ()) with _ -> -1 
-
-(* Theses functions need to be defined later in the code. *)
-let get_hostname = 
-  let f () = "Debug.get_hostname not set" in
-  ref f
 
 let associate_thread_with_task task = 
   let id = get_thread_id () in
@@ -81,8 +76,18 @@
   val name: string
 end
 
+let hostname_cache = ref None
+let hostname_m = Mutex.create ()
+let get_hostname () =
+  match Mutex.execute hostname_m (fun () -> !hostname_cache) with
+  | Some h -> h
+  | None ->
+               let h = Unix.gethostname () in
+               Mutex.execute hostname_m (fun () -> hostname_cache := Some h);
+               h
+let invalidate_hostname_cache () = Mutex.execute hostname_m (fun () -> 
hostname_cache := None)
+
 module Debugger = functor(Brand: BRAND) -> struct
-  let hostname = Unix.gethostname ()
   let _ =
     Mutex.execute dkmutex (fun () -> 
       debug_keys := StringSet.add Brand.name !debug_keys)
@@ -102,7 +107,7 @@
   let output (f:string -> ?extra:string -> ('a, unit, string, 'b) format4 -> 
'a) fmt =
     let extra = 
       Printf.sprintf "%s|%s|%s|%s" 
-      hostname
+      (get_hostname ())
       (get_thread_name ()) 
       (get_task ())
       Brand.name
@@ -112,7 +117,7 @@
        let output_and_return ?raw (f:string -> ?raw:bool -> ?extra:string -> 
('a, unit, string, 'b) format4 -> 'a) fmt =
     let extra =
       Printf.sprintf "%s|%s|%s|%s"
-      hostname
+      (get_hostname ())
       (get_thread_name ())
       (get_task ())
       Brand.name
diff -r da78a9af0fdf -r 06f4d30cef5f log/debug.mli
--- a/log/debug.mli     Fri Apr 09 10:49:50 2010 +0100
+++ b/log/debug.mli     Mon Apr 12 17:54:42 2010 +0100
@@ -13,6 +13,9 @@
  *)
 
 (** Debug utilities *)
+
+(** Throw away the cached hostname. The next log line will re-query the 
hostname *)
+val invalidate_hostname_cache: unit -> unit
 
 (** {2 Associate a task to the current actions} *)
 
2 files changed, 16 insertions(+), 8 deletions(-)
log/debug.ml  |   21 +++++++++++++--------
log/debug.mli |    3 +++

Attachment: xen-api-libs.hg.patch
Description: Text Data

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