2 files changed, 27 insertions, 7 deletions

diff --git a/src/periodic.c b/src/periodic.c
index 0291ff98..068f2a1e 100644
--- a/src/periodic.c
+++ b/src/periodic.c
@@ -57,6 +57,21 @@ iDefineTypeConstructionArgs(PeriodicCommand, (iAny *ctx, const char *cmd), ctx,
 
 static const uint32_t postingInterval_Periodic_ = 500;
 
+static void removePending_Periodic_(iPeriodic *d) {
+    iForEach(PtrSet, i, &d->pendingRemoval) {
+        size_t pos;
+        iPeriodicCommand key = { .context = *i.value };
+        if (locate_SortedArray(&d->commands, &key, &pos)) {
+            iPeriodicCommand *pc = at_SortedArray(&d->commands, pos);
+            deinit_PeriodicCommand(pc);
+            remove_Array(&d->commands.values, pos);
+        }
+    }
+    clear_PtrSet(&d->pendingRemoval);
+}
+
+static iBool isDispatching_;
+
 iBool dispatchCommands_Periodic(iPeriodic *d) {
     const uint32_t now = SDL_GetTicks();
     if (now - d->lastPostTime < postingInterval_Periodic_) {
@@ -65,20 +80,24 @@ iBool dispatchCommands_Periodic(iPeriodic *d) {
     d->lastPostTime = now;
     iBool wasPosted = iFalse;
     lock_Mutex(d->mutex);
+    isDispatching_ = iTrue;
+    iAssert(isEmpty_PtrSet(&d->pendingRemoval));
     iConstForEach(Array, i, &d->commands.values) {
         const iPeriodicCommand *pc = i.value;
+        iAssert(isInstance_Object(pc->context, &Class_Widget));
         const SDL_UserEvent ev = {
             .type  = SDL_USEREVENT,
             .code  = command_UserEventCode,
             .data1 = (void *) cstr_String(&pc->command),
             .data2 = findRoot_Window(get_Window(), pc->context)
         };
-        iAssert(isInstance_Object(pc->context, &Class_Widget));
         setCurrent_Root(ev.data2);
         dispatchEvent_Widget(pc->context, (const SDL_Event *) &ev);
         wasPosted = iTrue;
     }
+    removePending_Periodic_(d);
     setCurrent_Root(NULL);
+    isDispatching_ = iFalse;
     unlock_Mutex(d->mutex);
     return wasPosted;
 }
@@ -87,9 +106,11 @@ void init_Periodic(iPeriodic *d) {
     d->mutex = new_Mutex();
     init_SortedArray(&d->commands, sizeof(iPeriodicCommand), cmp_PeriodicCommand_);
     d->lastPostTime = 0;
+    init_PtrSet(&d->pendingRemoval);
 }
 
 void deinit_Periodic(iPeriodic *d) {
+    deinit_PtrSet(&d->pendingRemoval);
     iForEach(Array, i, &d->commands.values) {
         deinit_PeriodicCommand(i.value);
     }
@@ -115,12 +136,9 @@ void add_Periodic(iPeriodic *d, iAny *context, const char *command) {
 
 void remove_Periodic(iPeriodic *d, iAny *context) {
     lock_Mutex(d->mutex);
-    size_t pos;
-    iPeriodicCommand key = { .context = context };
-    if (locate_SortedArray(&d->commands, &key, &pos)) {
-        iPeriodicCommand *pc = at_SortedArray(&d->commands, pos);
-        deinit_PeriodicCommand(pc);
-        remove_Array(&d->commands.values, pos);
+    insert_PtrSet(&d->pendingRemoval, context);
+    if (!isDispatching_) {
+        removePending_Periodic_(d);
     }
     unlock_Mutex(d->mutex);
 }
diff --git a/src/periodic.h b/src/periodic.h
index 8886617b..3a0501d9 100644
--- a/src/periodic.h
+++ b/src/periodic.h
@@ -21,6 +21,7 @@ ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 
 #include <the_Foundation/mutex.h>
+#include <the_Foundation/ptrset.h>
 #include <the_Foundation/sortedarray.h>
 
 iDeclareType(Periodic)
@@ -31,6 +32,7 @@ struct Impl_Periodic {
     iMutex *     mutex;
     iSortedArray commands;
     uint32_t     lastPostTime;
+    iPtrSet      pendingRemoval; /* contexts */
 };
 
 void    init_Periodic   (iPeriodic *);