* kdb_db2.c (MAX_LOCK_TRIES): New macro.

(krb5_db2_db_lock): Always make non-blocking attempts to acquire the lock.
Retry up to MAX_LOCK_TRIES times on failure.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@17339 dc483132-0cff-0310-8789-dd5450dbe970

diff --git a/src/lib/kdb/kdb_db2/ChangeLog b/src/lib/kdb/kdb_db2/ChangeLog
index 1e23fa368229abd2a919a193abede7fa2643a71b..865aeef2daea9570f5262176d793324427cac811 100644 (file)
--- a/src/lib/kdb/kdb_db2/ChangeLog
+++ b/src/lib/kdb/kdb_db2/ChangeLog
@@ -1,3 +1,9 @@
+2005-08-19  Ken Raeburn  <raeburn@mit.edu>
+
+       * kdb_db2.c (MAX_LOCK_TRIES): New macro.
+       (krb5_db2_db_lock): Always make non-blocking attempts to acquire
+       the lock.  Retry up to MAX_LOCK_TRIES times on failure.
+
 2005-07-06  Ken Raeburn  <raeburn@mit.edu>
 
        * Makefile.in (LIBBASE): Change to db2.

diff --git a/src/lib/kdb/kdb_db2/kdb_db2.c b/src/lib/kdb/kdb_db2/kdb_db2.c
index 2bcfae1aad167b02435519ffacfb434d669e6a39..dc41a081caf87128856fc18ab019e95a5e2d3f3b 100644 (file)
--- a/src/lib/kdb/kdb_db2/kdb_db2.c
+++ b/src/lib/kdb/kdb_db2/kdb_db2.c
@@ -531,6 +531,8 @@ krb5_db2_db_end_update(krb5_context context)
     return (retval);
 }
 
+#define MAX_LOCK_TRIES 5
+
 krb5_error_code
 krb5_db2_db_lock(krb5_context context, int in_mode)
 {
@@ -540,7 +542,7 @@ krb5_db2_db_lock(krb5_context context, int in_mode)
     krb5_error_code retval;
     time_t  mod_time;
     kdb5_dal_handle *dal_handle;
-    int     mode = in_mode & ~KRB5_DB_LOCKMODE_PERMANENT;      /* permanent is not available for principal db */
+    int     mode, gotlock, tries;
 
     switch (in_mode) {
     case KRB5_DB_LOCKMODE_PERMANENT:
@@ -571,20 +573,24 @@ krb5_db2_db_lock(krb5_context context, int in_mode)
     if ((mode != KRB5_LOCKMODE_SHARED) && (mode != KRB5_LOCKMODE_EXCLUSIVE))
        return KRB5_KDB_BADLOCKMODE;
 
-    if (db_ctx->db_nb_locks)
-       krb5_lock_mode = mode | KRB5_LOCKMODE_DONTBLOCK;
-    else
-       krb5_lock_mode = mode;
-    retval = krb5_lock_file(context, db_ctx->db_lf_file, krb5_lock_mode);
-    switch (retval) {
-    case EBADF:
-       if (mode == KRB5_LOCKMODE_EXCLUSIVE)
+    krb5_lock_mode = mode | KRB5_LOCKMODE_DONTBLOCK;
+    for (gotlock = tries = 0; tries < MAX_LOCK_TRIES; tries++) {
+       retval = krb5_lock_file(context, db_ctx->db_lf_file, krb5_lock_mode);
+       if (retval == 0) {
+           gotlock++;
+           break;
+       } else if (retval == EBADF && mode == KRB5_DB_LOCKMODE_EXCLUSIVE)
+           /* tried to exclusive-lock something we don't have */
+           /* write access to */
            return KRB5_KDB_CANTLOCK_DB;
-    default:
-       return retval;
-    case 0:
-       break;
+       sleep(1);
     }
+    if (retval == EACCES)
+       return KRB5_KDB_CANTLOCK_DB;
+    else if (retval == EAGAIN || retval == EWOULDBLOCK)
+       return OSA_ADB_CANTLOCK_DB;
+    else if (retval != 0)
+       return retval;
 
     if ((retval = krb5_db2_db_get_age(context, NULL, &mod_time)))
        goto lock_error;