MonetDB: trails - Avoid race conditions with the scheduler's thr...

[Pedro Ferreira]

Changeset: dfddbb30687c for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=dfddbb30687c
Modified Files:
        sql/backends/monet5/sql_cquery.c
Branch: trails
Log Message:

Avoid race conditions with the scheduler's thread id


diffs (144 lines):

diff --git a/sql/backends/monet5/sql_cquery.c b/sql/backends/monet5/sql_cquery.c
--- a/sql/backends/monet5/sql_cquery.c
+++ b/sql/backends/monet5/sql_cquery.c
@@ -84,7 +84,7 @@ do {                                    
 } while(0);
 
 static void
-cleanBaskets(int idx)
+cleanBaskets(int idx) //Always called within a lock
 {
        int m, n, o, found;
        str sch, tbl;
@@ -109,7 +109,7 @@ cleanBaskets(int idx)
 }
 
 static void
-CQfree(Client cntxt, int idx)
+CQfree(Client cntxt, int idx) //Always called within a lock
 {
        int i;
        InstrPtr p;
@@ -304,7 +304,7 @@ CQlocateBasketExternal(str schname, str 
 }
 
 static int
-CQlocateAlias(str alias)
+CQlocateAlias(str alias) //Always called within a lock
 {
        int i;
        for (i = 0; i < pnettop; i++){
@@ -734,11 +734,9 @@ unlock:
        if(!msg && cq_pid == 0) { /* start the scheduler if needed */
                if( pnettop == 1)
                        pnstatus = CQINIT;
-               MT_lock_unset(&ttrLock);
                msg = CQstartScheduler();
-       } else {
-               MT_lock_unset(&ttrLock);
        }
+       MT_lock_unset(&ttrLock);
 finish:
        if(freeMB)
                freeMalBlk(be->mb);
@@ -804,10 +802,8 @@ CQresume(str alias, int with_alter, lng 
        }
 
        /* start the scheduler if needed */
-       if(cq_pid == 0) {
+       if(cq_pid == 0)
                msg = CQstartScheduler();
-       }
-
 unlock:
        MT_lock_unset(&ttrLock);
 finish:
@@ -836,12 +832,9 @@ CQresumeAll(void)
        }
 
        /* start the scheduler if needed */
-       if(cq_pid == 0) {
-               MT_lock_unset(&ttrLock);
+       if(cq_pid == 0)
                msg = CQstartScheduler();
-       } else {
-               MT_lock_unset(&ttrLock);
-       }
+       MT_lock_unset(&ttrLock);
        return msg;
 }
 
@@ -996,12 +989,13 @@ str
 CQheartbeat(Client cntxt, MalBlkPtr mb, MalStkPtr stk, InstrPtr pci)
 {
        str alias, msg = MAL_SUCCEED;
-       int j, there_is_window_constraint, idx=0, last= pnettop;
+       int j, there_is_window_constraint, idx=0, last;
        lng heartbeats;
        (void) cntxt;
        (void) mb;
 
        MT_lock_set(&ttrLock);
+       last = pnettop;
        if( pci->argc >2){
                alias = *getArgReference_str(stk,pci,1);
                idx = CQlocateAlias(alias);
@@ -1075,7 +1069,7 @@ CQderegister(Client cntxt, str alias)
 {
        int idx = 0, i, j;
        str msg = MAL_SUCCEED, this_alias = NULL, falias = NULL;
-       MT_Id myID = MT_getpid();
+       MT_Id myID = MT_getpid(), previous_scheduler_ID;
 
        MT_lock_set(&ttrLock);
        idx = CQlocateAlias(alias);
@@ -1116,11 +1110,10 @@ CQderegister(Client cntxt, str alias)
                }
                if( pnettop == 0) {
                        pnstatus = CQSTOP;
+                       previous_scheduler_ID = cq_pid;
                        MT_lock_unset(&ttrLock);
-                       if(cq_pid > 0) {
-                               MT_join_thread(cq_pid);
-                               cq_pid = 0;
-                       }
+                       if(previous_scheduler_ID > 0)
+                               MT_join_thread(previous_scheduler_ID);
                        goto finish;
                }
        } else {
@@ -1137,14 +1130,15 @@ CQderegisterAll(Client cntxt)
 {
        str msg = MAL_SUCCEED, this_alias = NULL;
        int i;
-       MT_Id myID = MT_getpid();
+       MT_Id myID = MT_getpid(), previous_scheduler_ID;
        //mvc* smvc;
        //ALL_ROOT_CHECK(cntxt, "cquery.deregisterall", "STOP ");
 
        MT_lock_set(&ttrLock);
+       previous_scheduler_ID = cq_pid;
 
        for(i = 0 ; i < pnettop; i++) {
-               if(myID != cq_pid) {
+               if(myID != previous_scheduler_ID) {
                        pnet[i].status = CQSTOP;
                        this_alias = pnet[i].alias;
                        MT_lock_unset(&ttrLock);
@@ -1161,13 +1155,11 @@ CQderegisterAll(Client cntxt)
                }
                i--;
        }
-       if(myID != cq_pid)
+       if(myID != previous_scheduler_ID)
                pnstatus = CQSTOP;
        MT_lock_unset(&ttrLock);
-       if(myID != cq_pid && cq_pid > 0) {
-               MT_join_thread(cq_pid);
-               cq_pid = 0;
-       }
+       if(myID != previous_scheduler_ID && previous_scheduler_ID > 0)
+               MT_join_thread(previous_scheduler_ID);
        return msg;
 }
 
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