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authorandreas_kupries <akupries@shaw.ca>2008-04-24 18:51:00 (GMT)
committerandreas_kupries <akupries@shaw.ca>2008-04-24 18:51:00 (GMT)
commit140933e5aa1698253bb1afadc0add0e4e068bfc9 (patch)
tree6ffa83cf83f35502a872f58569f03dd338cb3d18 /generic
parent2806530fd57fcf8fdf0f65ef7b2778bcadfaa8ed (diff)
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* tests/ioCmd.test: Extended testsuite for reflected channel
implementation. Added test cases about how it handles if the rug is pulled out from under a channel (= killing threads, interpreters containing the tcl command for a channel, and channel sitting in a different interpreter/thread.) * generic/tclIORChan.c: Fixed the bugs exposed by the new testcases, redone most of the cleanup and exit handling.
Diffstat (limited to 'generic')
-rw-r--r--generic/tclIORChan.c382
1 files changed, 334 insertions, 48 deletions
diff --git a/generic/tclIORChan.c b/generic/tclIORChan.c
index b57d157..0c9c96b 100644
--- a/generic/tclIORChan.c
+++ b/generic/tclIORChan.c
@@ -15,7 +15,7 @@
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
- * RCS: @(#) $Id: tclIORChan.c,v 1.30 2008/04/04 17:18:31 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclIORChan.c,v 1.31 2008/04/24 18:51:01 andreas_kupries Exp $
*/
#include <tclInt.h>
@@ -85,7 +85,11 @@ typedef struct {
Tcl_Channel chan; /* Back reference to generic channel
* structure. */
Tcl_Interp *interp; /* Reference to the interpreter containing the
- * Tcl level part of the channel. */
+ * Tcl level part of the channel. NULL here
+ * signals the channel is dead because the
+ * interpreter/thread containing its Tcl
+ * command is gone.
+ */
#ifdef TCL_THREADS
Tcl_ThreadId thread; /* Thread the 'interp' belongs to. */
#endif
@@ -338,6 +342,13 @@ typedef struct ForwardingEvent {
struct ForwardingResult {
Tcl_ThreadId src; /* Originating thread. */
Tcl_ThreadId dst; /* Thread the op was forwarded to. */
+ Tcl_Interp* dsti; /* Interpreter in the thread the op was forwarded to. */
+ /*
+ * Note regarding 'dsti' above: Its information is also available via the
+ * chain evPtr->rcPtr->interp, however, as can be seen, two more
+ * indirections are needed to retrieve it. And the evPtr may be gone,
+ * breaking the chain.
+ */
Tcl_Condition done; /* Condition variable the forwarder blocks
* on. */
int result; /* TCL_OK or TCL_ERROR */
@@ -347,6 +358,17 @@ struct ForwardingResult {
* results. */
};
+typedef struct ThreadSpecificData {
+ /*
+ * Table of all reflected channels owned by this thread. This is the
+ * per-thread version of the per-interpreter map.
+ */
+
+ ReflectedChannelMap* rcmPtr;
+} ThreadSpecificData;
+
+static Tcl_ThreadDataKey dataKey;
+
/*
* List of forwarded operations which have not completed yet, plus the mutex
* to protect the access to this process global list.
@@ -361,16 +383,15 @@ TCL_DECLARE_MUTEX(rcForwardMutex)
* the event function executed by the thread receiving a forwarding event
* (which executes the appropriate function and collects the result, if any).
*
- * The two ExitProcs are handlers so that things do not deadlock when either
- * thread involved in the forwarding exits. They also clean things up so that
- * we don't leak resources when threads go away.
+ * The ExitProc ensures that things do not deadlock when the sending thread
+ * involved in the forwarding exits. It also clean things up so that we don't
+ * leak resources when threads go away.
*/
static void ForwardOpToOwnerThread(ReflectedChannel *rcPtr,
ForwardedOperation op, const VOID *param);
static int ForwardProc(Tcl_Event *evPtr, int mask);
static void SrcExitProc(ClientData clientData);
-static void DstExitProc(ClientData clientData);
#define FreeReceivedError(p) \
if ((p)->base.mustFree) { \
@@ -395,6 +416,10 @@ static void DstExitProc(ClientData clientData);
(p)->base.msgStr = (char *) (emsg)
static void ForwardSetObjError(ForwardParam *p, Tcl_Obj *objPtr);
+
+static ReflectedChannelMap * GetThreadReflectedChannelMap(void);
+static void DeleteThreadReflectedChannelMap(ClientData clientData);
+
#endif /* TCL_THREADS */
#define SetChannelErrorStr(c,msgStr) \
@@ -437,9 +462,10 @@ static const char *msg_write_toomuch = "{write wrote more than requested}";
static const char *msg_write_nothing = "{write wrote nothing}";
static const char *msg_seek_beforestart = "{Tried to seek before origin}";
#ifdef TCL_THREADS
-static const char *msg_send_originlost = "{Origin thread lost}";
-static const char *msg_send_dstlost = "{Destination thread lost}";
+static const char *msg_send_originlost = "{Channel thread lost}";
+static const char *msg_send_dstlost = "{Owner lost}";
#endif /* TCL_THREADS */
+static const char *msg_dstlost = "-code 1 -level 0 -errorcode NONE -errorinfo {} -errorline 1 {Owner lost}";
/*
* Main methods to plug into the 'chan' ensemble'. ==================
@@ -696,6 +722,12 @@ TclChanCreateObjCmd(
}
}
Tcl_SetHashValue(hPtr, chan);
+#ifdef TCL_THREADS
+ rcmPtr = GetThreadReflectedChannelMap();
+ hPtr = Tcl_CreateHashEntry(&rcmPtr->map,
+ chanPtr->state->channelName, &isNew);
+ Tcl_SetHashValue(hPtr, chan);
+#endif
/*
* Return handle as result of command.
@@ -1026,8 +1058,8 @@ ReflectClose(
/*
* THREADED => Forward this to the origin thread
*
- * Note: Have a thread delete handler for the origin thread. Use this
- * to clean up the structure!
+ * Note: DeleteThreadReflectedChannelMap() is the thread exit handler for the origin
+ * thread. Use this to clean up the structure? Except if lost?
*/
#ifdef TCL_THREADS
@@ -1098,12 +1130,26 @@ ReflectClose(
* Remove the channel from the map before releasing the memory, to
* prevent future accesses (like by 'postevent') from finding and
* dereferencing a dangling pointer.
+ *
+ * NOTE: The channel may not be in the map. This is ok, that happens
+ * when the channel was created in a different interpreter and/or
+ * thread and then was moved here.
*/
rcmPtr = GetReflectedChannelMap (interp);
hPtr = Tcl_FindHashEntry (&rcmPtr->map,
Tcl_GetChannelName (rcPtr->chan));
- Tcl_DeleteHashEntry (hPtr);
+ if (hPtr) {
+ Tcl_DeleteHashEntry (hPtr);
+ }
+#ifdef TCL_THREADS
+ rcmPtr = GetThreadReflectedChannelMap();
+ hPtr = Tcl_FindHashEntry (&rcmPtr->map,
+ Tcl_GetChannelName (rcPtr->chan));
+ if (hPtr) {
+ Tcl_DeleteHashEntry (hPtr);
+ }
+#endif
FreeReflectedChannel(rcPtr);
#ifdef TCL_THREADS
@@ -1169,6 +1215,7 @@ ReflectInput(
if (p.base.code != TCL_OK) {
PassReceivedError(rcPtr->chan, &p);
*errorCodePtr = EINVAL;
+ p.input.toRead = -1;
} else {
*errorCodePtr = EOK;
}
@@ -1263,6 +1310,7 @@ ReflectOutput(
if (p.base.code != TCL_OK) {
PassReceivedError(rcPtr->chan, &p);
*errorCodePtr = EINVAL;
+ p.output.toWrite = -1;
} else {
*errorCodePtr = EOK;
}
@@ -1361,6 +1409,7 @@ ReflectSeekWide(
if (p.base.code != TCL_OK) {
PassReceivedError(rcPtr->chan, &p);
*errorCodePtr = EINVAL;
+ p.seek.offset = -1;
} else {
*errorCodePtr = EOK;
}
@@ -2066,9 +2115,24 @@ InvokeTclMethod(
int result; /* Result code of method invokation */
Tcl_Obj *resObj = NULL; /* Result of method invokation. */
+ if (!rcPtr->interp) {
+ /*
+ * The channel is marked as dead. Bail out immediately, with an
+ * appropriate error.
+ */
+
+ if (resultObjPtr != NULL) {
+ resObj = Tcl_NewStringObj(msg_dstlost,-1);
+ *resultObjPtr = resObj;
+ Tcl_IncrRefCount(resObj);
+ }
+ return TCL_ERROR;
+ }
+
/*
* NOTE (5): Decide impl. issue: Cache objects with method names? Needs
* TSD data as reflections can be created in many different threads.
+ * NO: Caching of command resolutions means storage per channel.
*/
/*
@@ -2242,11 +2306,25 @@ DeleteReflectedChannelMap(
ReflectedChannelMap* rcmPtr; /* The map */
Tcl_HashSearch hSearch; /* Search variable. */
Tcl_HashEntry *hPtr; /* Search variable. */
+ ReflectedChannel* rcPtr;
+ Tcl_Channel chan;
+
+#ifdef TCL_THREADS
+ ForwardingResult *resultPtr;
+ ForwardingEvent *evPtr;
+ ForwardParam *paramPtr;
+#endif
/*
- * Delete all entries. The channels may have been closed alreay, or will
+ * Delete all entries. The channels may have been closed already, or will
* be closed later, by the standard IO finalization of an interpreter
- * under destruction.
+ * under destruction. Except for the channels which were moved to a
+ * different interpreter and/or thread. They do not exist from the IO
+ * systems point of view and will not get closed. Therefore mark all as
+ * dead so that any future access will cause a proper error. For channels
+ * in a different thread we actually do the same as
+ * DeleteThreadReflectedChannelMap(), just restricted to the channels of
+ * this interp.
*/
rcmPtr = clientData;
@@ -2254,13 +2332,208 @@ DeleteReflectedChannelMap(
hPtr != NULL;
hPtr = Tcl_FirstHashEntry(&rcmPtr->map, &hSearch)) {
+ chan = (Tcl_Channel) Tcl_GetHashValue (hPtr);
+ rcPtr = (ReflectedChannel *) Tcl_GetChannelInstanceData(chan);
+
+ rcPtr->interp = NULL;
+
Tcl_DeleteHashEntry(hPtr);
}
Tcl_DeleteHashTable(&rcmPtr->map);
ckfree((char *) &rcmPtr->map);
+
+#ifdef TCL_THREADS
+ /*
+ * The origin interpreter for one or more reflected channels is gone.
+ */
+
+ /*
+ * Go through the list of pending results and cancel all whose events were
+ * destined for this interpreter. While this is in progress we block any
+ * other access to the list of pending results.
+ */
+
+ Tcl_MutexLock(&rcForwardMutex);
+
+ for (resultPtr = forwardList;
+ resultPtr != NULL;
+ resultPtr = resultPtr->nextPtr) {
+ if (resultPtr->dsti != interp) {
+ /* Ignore results/events for other interpreters. */
+ continue;
+ }
+
+ /*
+ * The receiver for the event exited, before processing the event. We
+ * detach the result now, wake the originator up and signal failure.
+ */
+
+ evPtr = resultPtr->evPtr;
+ paramPtr = evPtr->param;
+
+ evPtr->resultPtr = NULL;
+ resultPtr->evPtr = NULL;
+ resultPtr->result = TCL_ERROR;
+
+ ForwardSetStaticError(paramPtr, msg_send_dstlost);
+
+ Tcl_ConditionNotify(&resultPtr->done);
+ }
+
+ /*
+ * Get the map of all channels handled by the current thread. This is a
+ * ReflectedChannelMap, but on a per-thread basis, not per-interp. Go
+ * through the channels and remove all which were handled by this
+ * interpreter. They have already been marked as dead.
+ */
+
+ rcmPtr = GetThreadReflectedChannelMap();
+ for (hPtr = Tcl_FirstHashEntry(&rcmPtr->map, &hSearch);
+ hPtr != NULL;
+ hPtr = Tcl_NextHashEntry(&hSearch)) {
+
+ chan = (Tcl_Channel) Tcl_GetHashValue (hPtr);
+ rcPtr = (ReflectedChannel *) Tcl_GetChannelInstanceData(chan);
+
+ if (rcPtr->interp != interp) {
+ /* Ignore entries for other interpreters */
+ continue;
+ }
+
+ Tcl_DeleteHashEntry(hPtr);
+ }
+
+ Tcl_MutexUnlock(&rcForwardMutex);
+#endif
}
#ifdef TCL_THREADS
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetThreadReflectedChannelMap --
+ *
+ * Gets and potentially initializes the reflected channel map for a
+ * thread.
+ *
+ * Results:
+ * A pointer to the map created, for use by the caller.
+ *
+ * Side effects:
+ * Initializes the reflected channel map for a thread.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static ReflectedChannelMap *
+GetThreadReflectedChannelMap()
+{
+ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+
+ if (!tsdPtr->rcmPtr) {
+ tsdPtr->rcmPtr = (ReflectedChannelMap *) ckalloc(sizeof(ReflectedChannelMap));
+ Tcl_InitHashTable(&tsdPtr->rcmPtr->map, TCL_STRING_KEYS);
+ Tcl_CreateThreadExitHandler(DeleteThreadReflectedChannelMap, NULL);
+ }
+
+ return tsdPtr->rcmPtr;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * DeleteThreadReflectedChannelMap --
+ *
+ * Deletes the channel table for a thread. This procedure is invoked when
+ * a thread is deleted. The channels have already been marked as dead, in
+ * DeleteReflectedChannelMap().
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * Deletes the hash table of channels.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+DeleteThreadReflectedChannelMap(
+ ClientData clientData) /* The per-thread data structure. */
+{
+ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+ Tcl_HashSearch hSearch; /* Search variable. */
+ Tcl_HashEntry *hPtr; /* Search variable. */
+ Tcl_ThreadId self = Tcl_GetCurrentThread();
+
+ ReflectedChannelMap* rcmPtr; /* The map */
+ Tcl_Channel chan;
+ ReflectedChannel* rcPtr;
+ ForwardingResult *resultPtr;
+ ForwardingEvent *evPtr;
+ ForwardParam *paramPtr;
+
+ /*
+ * The origin thread for one or more reflected channels is gone.
+ * NOTE: If this function is called due to a thread getting killed the
+ * per-interp DeleteReflectedChannelMap is apparently not called.
+ */
+
+ /*
+ * Go through the list of pending results and cancel all whose events were
+ * destined for this thread. While this is in progress we block any
+ * other access to the list of pending results.
+ */
+
+ Tcl_MutexLock(&rcForwardMutex);
+
+ for (resultPtr = forwardList;
+ resultPtr != NULL;
+ resultPtr = resultPtr->nextPtr) {
+ if (resultPtr->dst != self) {
+ /* Ignore results/events for other threads. */
+ continue;
+ }
+
+ /*
+ * The receiver for the event exited, before processing the event. We
+ * detach the result now, wake the originator up and signal failure.
+ */
+
+ evPtr = resultPtr->evPtr;
+ paramPtr = evPtr->param;
+
+ evPtr->resultPtr = NULL;
+ resultPtr->evPtr = NULL;
+ resultPtr->result = TCL_ERROR;
+
+ ForwardSetStaticError(paramPtr, msg_send_dstlost);
+
+ Tcl_ConditionNotify(&resultPtr->done);
+ }
+
+ /*
+ * Get the map of all channels handled by the current thread. This is a
+ * ReflectedChannelMap, but on a per-thread basis, not per-interp. Go
+ * through the channels, remove all, mark them as dead.
+ */
+
+ rcmPtr = GetThreadReflectedChannelMap();
+ for (hPtr = Tcl_FirstHashEntry(&rcmPtr->map, &hSearch);
+ hPtr != NULL;
+ hPtr = Tcl_FirstHashEntry(&rcmPtr->map, &hSearch)) {
+
+ chan = (Tcl_Channel) Tcl_GetHashValue (hPtr);
+ rcPtr = (ReflectedChannel *) Tcl_GetChannelInstanceData(chan);
+
+ rcPtr->interp = NULL;
+
+ Tcl_DeleteHashEntry(hPtr);
+ }
+
+ Tcl_MutexUnlock(&rcForwardMutex);
+}
+
static void
ForwardOpToOwnerThread(
ReflectedChannel *rcPtr, /* Channel instance */
@@ -2273,6 +2546,24 @@ ForwardOpToOwnerThread(
int result;
/*
+ * We gather the lock early. This allows us to check the liveness of the
+ * channel without interference from DeleteThreadReflectedChannelMap().
+ */
+
+ Tcl_MutexLock(&rcForwardMutex);
+
+ if (rcPtr->interp == NULL) {
+ /*
+ * The channel is marked as dead. Bail out immediately, with an
+ * appropriate error. Do not forget to unlock the mutex on this path.
+ */
+
+ ForwardSetStaticError((ForwardParam *)param, msg_send_dstlost);
+ Tcl_MutexUnlock(&rcForwardMutex);
+ return;
+ }
+
+ /*
* Create and initialize the event and data structures.
*/
@@ -2285,8 +2576,9 @@ ForwardOpToOwnerThread(
evPtr->rcPtr = rcPtr;
evPtr->param = (ForwardParam *) param;
- resultPtr->src = Tcl_GetCurrentThread();
- resultPtr->dst = dst;
+ resultPtr->src = Tcl_GetCurrentThread();
+ resultPtr->dst = dst;
+ resultPtr->dsti = rcPtr->interp;
resultPtr->done = NULL;
resultPtr->result = -1;
resultPtr->evPtr = evPtr;
@@ -2295,16 +2587,18 @@ ForwardOpToOwnerThread(
* Now execute the forward.
*/
- Tcl_MutexLock(&rcForwardMutex);
TclSpliceIn(resultPtr, forwardList);
+ /* Do not unlock here. That is done by the ConditionWait */
/*
- * Ensure cleanup of the event if any of the two involved threads exits
- * while this event is pending or in progress.
+ * Ensure cleanup of the event if the origin thread exits while this event
+ * is pending or in progress. Exitus of the destination thread is handled
+ * by DeleteThreadReflectionChannelMap(), this is set up by
+ * GetThreadReflectedChannelMap(). This is what we use the 'forwardList'
+ * (see above) for.
*/
Tcl_CreateThreadExitHandler(SrcExitProc, (ClientData) evPtr);
- Tcl_CreateThreadExitHandler(DstExitProc, (ClientData) evPtr);
/*
* Queue the event and poke the other thread's notifier.
@@ -2323,6 +2617,9 @@ ForwardOpToOwnerThread(
* NOTE (1): Is it possible that the current thread goes away while
* waiting here? IOW Is it possible that "SrcExitProc" is called while
* we are here? See complementary note (2) in "SrcExitProc"
+ *
+ * The ConditionWait unlocks the mutex during the wait and relocks it
+ * immediately after.
*/
Tcl_ConditionWait(&resultPtr->done, &rcForwardMutex, NULL);
@@ -2330,6 +2627,7 @@ ForwardOpToOwnerThread(
/*
* Unlink result from the forwarder list.
+ * No need to lock. Either still locked, or locked by the ConditionWait
*/
TclSpliceOut(resultPtr, forwardList);
@@ -2341,14 +2639,13 @@ ForwardOpToOwnerThread(
Tcl_ConditionFinalize(&resultPtr->done);
/*
- * Kill the cleanup handlers now, and the result structure as well, before
+ * Kill the cleanup handler now, and the result structure as well, before
* returning the success code.
*
* Note: The event structure has already been deleted.
*/
Tcl_DeleteThreadExitHandler(SrcExitProc, (ClientData) evPtr);
- Tcl_DeleteThreadExitHandler(DstExitProc, (ClientData) evPtr);
result = resultPtr->result;
ckfree((char*) resultPtr);
@@ -2378,6 +2675,8 @@ ForwardProc(
Tcl_Interp *interp = rcPtr->interp;
ForwardParam *paramPtr = evPtr->param;
Tcl_Obj *resObj = NULL; /* Interp result of InvokeTclMethod */
+ ReflectedChannelMap* rcmPtr; /* Map of reflected channels with handlers in this interp */
+ Tcl_HashEntry* hPtr; /* Entry in the above map */
/*
* Ignore the event if no one is waiting for its result anymore.
@@ -2411,8 +2710,22 @@ ForwardProc(
* Freeing is done here, in the origin thread, because the argv[]
* objects belong to this thread. Deallocating them in a different
* thread is not allowed
+ *
+ * We remove the channel from both interpreter and thread maps before
+ * releasing the memory, to prevent future accesses (like by
+ * 'postevent') from finding and dereferencing a dangling pointer.
*/
+ rcmPtr = GetReflectedChannelMap (interp);
+ hPtr = Tcl_FindHashEntry (&rcmPtr->map,
+ Tcl_GetChannelName (rcPtr->chan));
+ Tcl_DeleteHashEntry (hPtr);
+
+ rcmPtr = GetThreadReflectedChannelMap();
+ hPtr = Tcl_FindHashEntry (&rcmPtr->map,
+ Tcl_GetChannelName (rcPtr->chan));
+ Tcl_DeleteHashEntry (hPtr);
+
FreeReflectedChannel(rcPtr);
break;
@@ -2674,33 +2987,6 @@ SrcExitProc(
}
static void
-DstExitProc(
- ClientData clientData)
-{
- ForwardingEvent *evPtr = (ForwardingEvent *) clientData;
- ForwardingResult *resultPtr = evPtr->resultPtr;
- ForwardParam *paramPtr = evPtr->param;
-
- /*
- * NOTE (3): It is not clear if the event still exists when this handler
- * is called. We might have to use 'resultPtr' as our clientData instead.
- */
-
- /*
- * The receiver for the event exited, before processing the event. We
- * detach the result now, wake the originator up and signal failure.
- */
-
- evPtr->resultPtr = NULL;
- resultPtr->evPtr = NULL;
- resultPtr->result = TCL_ERROR;
-
- ForwardSetStaticError(paramPtr, msg_send_dstlost);
-
- Tcl_ConditionNotify(&resultPtr->done);
-}
-
-static void
ForwardSetObjError(
ForwardParam *paramPtr,
Tcl_Obj *obj)