make MaxMessages work for new mails as well

this helps enormously on the first sync of a 100k message box with a
limit of 1k messages. it also happens to make the syncing idempotent.

in a few conditionals we now explicitly test for max_messages being
enabled, not smaxxuid != 0, as after the initial fetch with no important
messages smaxxuid is zero, but we still have to skip over 99k messages
in the above case.

src/run-tests.pl

@@ -174,7 +174,7 @@ test("slave max size", \@X11, \@X22, @O22);
 
 my @x30 = (
  [ 0,
-   1, 0, "F", 2, 0, "S", 3, 0, "S", 4, 0, "", 5, 0, "" ],
+   1, 0, "F", 2, 0, "", 3, 0, "S", 4, 0, "", 5, 0, "S", 6, 0, "" ],
  [ 0,
    ],
  [ 0, 0, 0,
@@ -184,26 +184,16 @@ my @x30 = (
 my @O31 = ("", "", "MaxMessages 3\n");
 #show("30", "31", "31");
 my @X31 = (
+ [ 6,
+   1, 1, "F", 2, 2, "", 3, 3, "S", 4, 4, "", 5, 5, "S", 6, 6, "" ],
  [ 5,
-   1, 1, "F", 2, 2, "S", 3, 3, "S", 4, 4, "", 5, 5, "" ],
+   1, 1, "F", 2, 2, "", 4, 3, "", 5, 4, "S", 6, 5, "" ],
- [ 5,
+ [ 6, 2, 0,
-   1, 1, "F", 2, 2, "S", 3, 3, "S", 4, 4, "", 5, 5, "" ],
+   1, 1, "F", 2, 2, "", 4, 3, "", 5, 4, "S", 6, 5, "" ],
- [ 5, 0, 0,
-   1, 1, "F", 2, 2, "S", 3, 3, "S", 4, 4, "", 5, 5, "" ],
 );
 test("max messages", \@x30, \@X31, @O31);
 
-my @O41 = ("", "", "MaxMessages 3\nExpunge Both\n");
+test("max messages verification", \@X31, \@X31, @O31);
-#show("40", "41", "41");
-my @X41 = (
- [ 5,
-   1, 1, "F", 2, 2, "S", 3, 3, "S", 4, 4, "", 5, 5, "" ],
- [ 5,
-   1, 1, "F", 3, 3, "S", 4, 4, "", 5, 5, "" ],
- [ 5, 2, 0,
-   1, 1, "F", 3, 3, "S", 4, 4, "", 5, 5, "" ],
-);
-test("max messages catch-up", \@X31, \@X41, @O41);
 
 my @x50 = (
  [ 6,

src/sync.c

@@ -155,8 +155,10 @@ typedef struct {
 	int flags_total[2], flags_done[2];
 	int trash_total[2], trash_done[2];
 	int maxuid[2]; /* highest UID that was already propagated */
+	int newmaxuid[2]; /* highest UID that is currently being propagated */
 	int uidval[2]; /* UID validity value */
 	int newuid[2]; /* TUID lookup makes sense only for UIDs >= this */
+	int mmaxxuid; /* highest expired UID on master during new message propagation */
 	int smaxxuid; /* highest expired UID on slave */
 } sync_vars_t;
 
@@ -806,6 +808,9 @@ box_selected( int sts, void *aux )
 			goto bail;
 		}
 	}
+	svars->newmaxuid[M] = svars->maxuid[M];
+	svars->newmaxuid[S] = svars->maxuid[S];
+	svars->mmaxxuid = INT_MAX;
 	line = 0;
 	if ((jfp = fopen( svars->jname, "r" ))) {
 		if (!stat( svars->nname, &st ) && fgets( buf, sizeof(buf), jfp )) {
@@ -829,7 +834,7 @@ box_selected( int sts, void *aux )
 				}
 				if (buf[0] == '#' ?
 				      (t3 = 0, (sscanf( buf + 2, "%d %d %n", &t1, &t2, &t3 ) < 2) || !t3 || (t - t3 != TUIDL + 3)) :
-				      buf[0] == '(' || buf[0] == ')' || buf[0] == '{' || buf[0] == '}' ?
+				      buf[0] == '(' || buf[0] == ')' || buf[0] == '{' || buf[0] == '}' || buf[0] == '!' ?
 				        (sscanf( buf + 2, "%d", &t1 ) != 1) :
 				        buf[0] == '+' || buf[0] == '&' || buf[0] == '-' || buf[0] == '|' || buf[0] == '/' || buf[0] == '\\' ?
 				          (sscanf( buf + 2, "%d %d", &t1, &t2 ) != 2) :
@@ -846,6 +851,8 @@ box_selected( int sts, void *aux )
 					svars->newuid[M] = t1;
 				else if (buf[0] == '}')
 					svars->newuid[S] = t1;
+				else if (buf[0] == '!')
+					svars->smaxxuid = t1;
 				else if (buf[0] == '|') {
 					svars->uidval[M] = t1;
 					svars->uidval[S] = t2;
@@ -853,6 +860,10 @@ box_selected( int sts, void *aux )
 					srec = nfmalloc( sizeof(*srec) );
 					srec->uid[M] = t1;
 					srec->uid[S] = t2;
+					if (svars->newmaxuid[M] < t1)
+						svars->newmaxuid[M] = t1;
+					if (svars->newmaxuid[S] < t2)
+						svars->newmaxuid[S] = t2;
 					debug( "  new entry(%d,%d)\n", t1, t2 );
 					srec->msg[M] = srec->msg[S] = 0;
 					srec->status = 0;
@@ -876,6 +887,8 @@ box_selected( int sts, void *aux )
 					switch (buf[0]) {
 					case '-':
 						debug( "killed\n" );
+						if (srec->msg[M])
+							srec->msg[M]->srec = 0;
 						srec->status = S_DEAD;
 						break;
 					case '#':
@@ -1014,7 +1027,7 @@ box_selected( int sts, void *aux )
 	mexcs = 0;
 	nmexcs = rmexcs = 0;
 	if (svars->ctx[M]->opts & OPEN_OLD) {
-		if (svars->smaxxuid) {
+		if (chan->max_messages) {
 			/* When messages have been expired on the slave, the master fetch is split into
 			 * two ranges: The bulk fetch which corresponds with the most recent messages, and an
 			 * exception list of messages which would have been expired if they weren't important. */
@@ -1198,10 +1211,14 @@ box_loaded( int sts, void *aux )
 			 * - message is old (> 0) or expired (0) => ignore
 			 * - message was skipped (-1) => ReNew
 			 * - message was attempted, but failed (-2) => New
-			 * If new have no srec, the message is always New. */
+			 * If new have no srec, the message is always New. If messages were previously ignored
+			 * due to being excessive, they would now appear to be newer than the messages that
+			 * got actually synced, so make sure to look only at the newest ones. As some messages
+			 * may be already propagated before an interruption, and maxuid logging is delayed,
+			 * we need to track the newmaxuid separately. */
 			srec = tmsg->srec;
 			if (srec ? srec->uid[t] < 0 && (svars->chan->ops[t] & (srec->uid[t] == -1 ? OP_RENEW : OP_NEW))
-			         : (svars->chan->ops[t] & OP_NEW)) {
+			         : svars->newmaxuid[1-t] < tmsg->uid && (svars->chan->ops[t] & OP_NEW)) {
 				debug( "new message %d on %s\n", tmsg->uid, str_ms[1-t] );
 				if ((svars->chan->ops[t] & OP_EXPUNGE) && (tmsg->flags & F_DELETED))
 					debug( "  -> not %sing - would be expunged anyway\n", str_hl[t] );
@@ -1220,7 +1237,11 @@ box_loaded( int sts, void *aux )
 						srec->tuid[0] = 0;
 						srec->uid[1-t] = tmsg->uid;
 						srec->uid[t] = -2;
+						srec->msg[1-t] = tmsg;
+						srec->msg[t] = 0;
 						tmsg->srec = srec;
+						if (svars->newmaxuid[1-t] < tmsg->uid)
+							svars->newmaxuid[1-t] = tmsg->uid;
 						Fprintf( svars->jfp, "+ %d %d\n", srec->uid[M], srec->uid[S] );
 						debug( "  -> pair(%d,%d) created\n", srec->uid[M], srec->uid[S] );
 					}
@@ -1346,6 +1367,10 @@ box_loaded( int sts, void *aux )
 				alive++;
 			}
 		}
+		for (tmsg = svars->ctx[M]->msgs; tmsg; tmsg = tmsg->next) {
+			if ((srec = tmsg->srec) && srec->tuid[0] && !(tmsg->flags & F_DELETED))
+				alive++;
+		}
 		todel = alive - svars->chan->max_messages;
 		debug( "%d alive messages, %d excess - expiring\n", alive, todel );
 		for (tmsg = svars->ctx[S]->msgs; tmsg; tmsg = tmsg->next) {
@@ -1353,6 +1378,7 @@ box_loaded( int sts, void *aux )
 				continue;
 			if (!(srec = tmsg->srec) || srec->uid[M] <= 0) {
 				/* We did not push the message, so it must be kept. */
+				debug( "  old pair(%d,%d) unpropagated\n", srec->uid[M], srec->uid[S] );
 				todel--;
 			} else {
 				nflags = (tmsg->flags | srec->aflags[S]) & ~srec->dflags[S];
@@ -1360,13 +1386,32 @@ box_loaded( int sts, void *aux )
 					/* The message is not deleted, or is already (being) expired. */
 					if ((nflags & F_FLAGGED) || !(nflags & F_SEEN)) {
 						/* Important messages are always kept. */
+						debug( "  old pair(%d,%d) important\n", srec->uid[M], srec->uid[S] );
 						todel--;
 					} else if (todel > 0 ||
 					           ((srec->status & (S_EXPIRE|S_EXPIRED)) == (S_EXPIRE|S_EXPIRED)) ||
 					           ((srec->status & (S_EXPIRE|S_EXPIRED)) && (tmsg->flags & F_DELETED))) {
 						/* The message is excess or was already (being) expired. */
 						srec->status |= S_NEXPIRE;
-						debug( "  pair(%d,%d)\n", srec->uid[M], srec->uid[S] );
+						debug( "  old pair(%d,%d) expired\n", srec->uid[M], srec->uid[S] );
+						todel--;
+					}
+				}
+			}
+		}
+		for (tmsg = svars->ctx[M]->msgs; tmsg; tmsg = tmsg->next) {
+			if ((srec = tmsg->srec) && srec->tuid[0]) {
+				nflags = tmsg->flags;
+				if (!(nflags & F_DELETED)) {
+					if ((nflags & F_FLAGGED) || !(nflags & F_SEEN)) {
+						/* Important messages are always fetched. */
+						debug( "  new pair(%d,%d) important\n", srec->uid[M], srec->uid[S] );
+						todel--;
+					} else if (todel > 0) {
+						/* The message is excess. */
+						srec->status |= S_NEXPIRE;
+						debug( "  new pair(%d,%d) expired\n", srec->uid[M], srec->uid[S] );
+						svars->mmaxxuid = srec->uid[M];
 						todel--;
 					}
 				}
@@ -1374,7 +1419,10 @@ box_loaded( int sts, void *aux )
 		}
 		debug( "%d excess messages remain\n", todel );
 		for (srec = svars->srecs; srec; srec = srec->next) {
-			if ((srec->status & (S_DEAD|S_DONE)) || !srec->msg[S])
+			if (srec->status & S_DEAD)
+				continue;
+			if (!srec->tuid[0]) {
+				if (!srec->msg[S])
 					continue;
 				nex = (srec->status / S_NEXPIRE) & 1;
 				if (nex != ((srec->status / S_EXPIRED) & 1)) {
@@ -1392,6 +1440,14 @@ box_loaded( int sts, void *aux )
 					/* Note: the "wrong" transaction may be pending here,
 					 * e.g.: S_NEXPIRE = 0, S_EXPIRE = 1, S_EXPIRED = 0. */
 				}
+			} else {
+				if (srec->status & S_NEXPIRE) {
+					Fprintf( svars->jfp, "- %d %d\n", srec->uid[M], srec->uid[S] );
+					debug( "  pair(%d,%d): 1 (abort)\n", srec->uid[M], srec->uid[S] );
+					srec->msg[M]->srec = 0;
+					srec->status = S_DEAD;
+				}
+			}
 		}
 	}
 
@@ -1515,6 +1571,16 @@ msg_copied_p2( sync_vars_t *svars, sync_rec_t *srec, int t, int uid )
 		srec->uid[t] = uid;
 		srec->tuid[0] = 0;
 	}
+	if (t == S && svars->mmaxxuid < srec->uid[M]) {
+		/* If we have so many new messages that some of them are instantly expired,
+		 * but some are still propagated because they are important, we need to
+		 * ensure explicitly that the bulk fetch limit is upped. */
+		svars->mmaxxuid = INT_MAX;
+		if (svars->smaxxuid < srec->uid[S] - 1) {
+			svars->smaxxuid = srec->uid[S] - 1;
+			Fprintf( svars->jfp, "! %d\n", svars->smaxxuid );
+		}
+	}
 }
 
 static void msgs_found_new( int sts, void *aux );
@@ -1735,13 +1801,14 @@ box_closed_p2( sync_vars_t *svars, int t )
 	if (!(svars->state[1-t] & ST_CLOSED))
 		return;
 
-	if (((svars->state[M] | svars->state[S]) & ST_DID_EXPUNGE) || svars->smaxxuid) {
+	if (((svars->state[M] | svars->state[S]) & ST_DID_EXPUNGE) || svars->chan->max_messages) {
 		/* This cleanup is not strictly necessary, as the next full sync
 		   would throw out the dead entries anyway. But ... */
+		debug( "purging obsolete entries\n" );
 
 		minwuid = INT_MAX;
-		if (svars->smaxxuid) {
+		if (svars->chan->max_messages) {
-			debug( "preparing entry purge - max expired slave uid is %d\n", svars->smaxxuid );
+			debug( "  max expired slave uid is %d\n", svars->smaxxuid );
 			for (srec = svars->srecs; srec; srec = srec->next) {
 				if (srec->status & S_DEAD)
 					continue;