From 1c12d490ff6ac2005173a695fa1bf4bb561c8066 Mon Sep 17 00:00:00 2001
From: Enrico Tassi <enrico.tassi@inria.fr>
Date: Sat, 8 Sep 2007 17:22:34 +0000
Subject: [PATCH] matita can now safely start a matitac that will put metadata
 in the right db.

---
 components/hmysql/hSqlite3.ml | 39 ++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/components/hmysql/hSqlite3.ml b/components/hmysql/hSqlite3.ml
index d5c5f0fcc..0038c650f 100644
--- a/components/hmysql/hSqlite3.ml
+++ b/components/hmysql/hSqlite3.ml
@@ -54,19 +54,44 @@ let quick_connect
 = 
   let username = Helm_registry.get "user.name" in
   let host_mangled = Pcre.replace ~pat:"[/ .]" ~templ:"_" host in
-  let tmp_db_name = 
-    "/dev/shm/matita.db." ^ username ^ "." ^ host_mangled ^ "." ^
-    string_of_int (Unix.getpid ())
+  let find_db _ = 
+    let base = "matita.db." ^ username ^ "." ^ host_mangled ^ "." in
+    let root = "/dev/shm/" in
+    let files = HExtlib.find ~test:(Pcre.pmatch ~pat:(base^"[0-9]+")) root in
+    let rec aux = function
+      | [] -> 
+         HLog.debug ("HSqlite3: no valid db files found in memory");
+         let name = root ^ base ^ string_of_int (Unix.getpid ()) in
+         HLog.debug ("HSqlite3: memory db file name: "^name);
+         name, true
+      | x::tl -> 
+         HLog.debug ("HSqlite3: found a .db in memory: " ^ x);
+         match Array.to_list (Pcre.extract ~pat:"\\.([0-9]+)$" x) with
+         | [] | _::_::_::_ -> assert false
+         | [_;p] when HExtlib.is_dir ("/proc/" ^ p) -> 
+            HLog.debug ("HSqlite3: found valid db file: " ^ x);
+            x, false
+         | _ ->
+            HLog.warn ("HSqlite3: dead process db file found: " ^ x);
+            HLog.warn ("HSqlite3: ignoring: " ^ x);
+            aux tl
+    in
+      aux files
   in
   let db_name = host ^ "/" ^ database in
   let db_to_open =
     if HExtlib.is_dir "/dev/shm/" && HExtlib.writable_dir "/dev/shm/" 
        && (not is_library) 
-    then
-      (let cp_to_ram_cmd = "cp " ^ db_name ^ " " ^ tmp_db_name in
-      ignore (Sys.command cp_to_ram_cmd);
+    then (
+      let tmp_db_name, first_time = find_db () in      
+      let cp_to_ram_cmd = "cp " ^ db_name ^ " " ^ tmp_db_name in
+      if first_time then 
+        if HExtlib.is_regular db_name then ignore (Sys.command cp_to_ram_cmd)
+        else HLog.debug ("HSqlite3: no initial db: " ^ db_name)
+      else HLog.debug "HSqlite3: not copying the db, already in memory";
       let mv_to_disk_cmd _ = 
-        ignore (Sys.command ("mv " ^ tmp_db_name ^ " " ^ db_name)) 
+        if first_time then ignore (Sys.command ("mv "^tmp_db_name^" "^db_name)) 
+        else HLog.debug "HSqlite3: not copying back the db"
       in
       at_exit mv_to_disk_cmd;
       tmp_db_name)
-- 
2.39.2