# HG changeset patch
# User Timo Sirainen <tss@iki.fi>
# Date 1043127455 -7200
# Node ID 21788a1e9e3902ae265dff0b65bcb83c552b9508
# Parent  9c8df18fb2a9324b5dba7f3d63dbb038cbcf61f4
Partial fetches are working fast again - faster than ever actually.

diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/imap/client.h
--- a/src/imap/client.h	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/imap/client.h	Tue Jan 21 07:37:35 2003 +0200
@@ -16,6 +16,7 @@
 
 	struct mail_storage *storage;
 	struct mailbox *mailbox;
+	unsigned int select_counter; /* increased when mailbox is changed */
 
 	time_t last_input;
 	unsigned int bad_counter;
diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/imap/cmd-select.c
--- a/src/imap/cmd-select.c	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/imap/cmd-select.c	Tue Jan 21 07:37:35 2003 +0200
@@ -36,6 +36,7 @@
 	/* set client's mailbox only after getting status to make sure
 	   we're not sending any expunge/exists replies too early to client */
 	client->mailbox = box;
+	client->select_counter++;
 
 	client_send_mailbox_flags(client, box, status.custom_flags,
 				  status.custom_flags_count);
diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/imap/imap-fetch-body-section.c
--- a/src/imap/imap-fetch-body-section.c	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/imap/imap-fetch-body-section.c	Tue Jan 21 07:37:35 2003 +0200
@@ -31,6 +31,46 @@
 	int (*match_func) (const char *const *, const unsigned char *, size_t);
 };
 
+struct partial_cache {
+	unsigned int select_counter;
+	unsigned int uid;
+
+	uoff_t physical_start;
+	struct message_size pos;
+};
+
+static struct partial_cache partial = { 0, 0, 0, { 0, 0, 0 } };
+
+static int seek_partial(unsigned int select_counter, unsigned int uid,
+			struct partial_cache *partial, struct istream *stream,
+			uoff_t physical_start, uoff_t virtual_skip)
+{
+	int cr_skipped;
+
+	if (select_counter == partial->select_counter && uid == partial->uid &&
+	    physical_start == partial->physical_start &&
+	    virtual_skip >= partial->pos.virtual_size) {
+		/* we can use the cache */
+		virtual_skip -= partial->pos.virtual_size;
+	} else {
+		partial->select_counter = select_counter;
+		partial->uid = uid;
+		partial->physical_start = physical_start;
+		memset(&partial->pos, 0, sizeof(partial->pos));
+	}
+
+	i_warning("skipping %lld", virtual_skip);
+
+	i_stream_seek(stream, partial->physical_start +
+		      partial->pos.physical_size);
+	message_skip_virtual(stream, virtual_skip, &partial->pos, &cr_skipped);
+
+	if (cr_skipped)
+		partial->pos.virtual_size--;
+
+	return cr_skipped;
+}
+
 /* fetch BODY[] or BODY[TEXT] */
 static int fetch_body(struct imap_fetch_context *ctx,
 		      const struct imap_fetch_body_data *body,
@@ -39,6 +79,8 @@
 	struct message_size hdr_size, body_size;
 	struct istream *stream;
 	const char *str;
+	int skip_cr;
+	off_t ret;
 
 	stream = mail->get_stream(mail, &hdr_size, &body_size);
 	if (stream == NULL)
@@ -54,9 +96,16 @@
 	if (o_stream_send_str(ctx->output, str) < 0)
 		return FALSE;
 
-	/* FIXME: SLOW! we need some cache for this. */
-	return message_send(ctx->output, stream, &body_size,
-			    body->skip, body->max_size);
+	skip_cr = seek_partial(ctx->select_counter, mail->uid,
+			       &partial, stream, 0, body->skip);
+	ret = message_send(ctx->output, stream, &body_size,
+			   skip_cr, body->max_size);
+	if (ret > 0) {
+		partial.pos.physical_size =
+			stream->v_offset - partial.physical_start;
+		partial.pos.virtual_size += ret;
+	}
+	return ret >= 0;
 }
 
 static const char **get_fields_array(const char *fields)
@@ -258,7 +307,7 @@
 		if (o_stream_send_str(ctx->output, str) < 0)
 			return FALSE;
 		return message_send(ctx->output, input, size,
-				    body->skip, body->max_size);
+				    body->skip, body->max_size) >= 0;
 	}
 
 	/* partial headers - copy the wanted fields into memory, inserting
@@ -386,23 +435,28 @@
 static int fetch_part_body(struct imap_fetch_context *ctx,
 			   struct istream *stream,
 			   const struct imap_fetch_body_data *body,
-			   const struct message_part *part)
+			   struct mail *mail, const struct message_part *part)
 {
 	const char *str;
-
-	/* jump to beginning of part body */
-	i_stream_seek(stream, part->physical_pos +
-		      part->header_size.physical_size);
+	int skip_cr;
+	off_t ret;
 
 	str = t_strdup_printf("%s {%"PRIuUOFF_T"}\r\n",
 			      ctx->prefix, part->body_size.virtual_size);
 	if (o_stream_send_str(ctx->output, str) < 0)
 		return FALSE;
 
-	/* FIXME: potential performance problem with big messages:
-	   FETCH BODY[1]<100000..1024>, hopefully no clients do this */
-	return message_send(ctx->output, stream, &part->body_size,
-			    body->skip, body->max_size);
+	skip_cr = seek_partial(ctx->select_counter, mail->uid,
+			       &partial, stream, part->physical_pos +
+			       part->header_size.physical_size, body->skip);
+	ret = message_send(ctx->output, stream, &part->body_size,
+			   skip_cr, body->max_size);
+	if (ret > 0) {
+		partial.pos.physical_size =
+			stream->v_offset - partial.physical_start;
+		partial.pos.virtual_size += ret;
+	}
+	return ret >= 0;
 }
 
 static int fetch_part(struct imap_fetch_context *ctx, struct mail *mail,
@@ -421,7 +475,7 @@
 		return FALSE;
 
 	if (*section == '\0' || strcmp(section, "TEXT") == 0)
-		return fetch_part_body(ctx, stream, body, part);
+		return fetch_part_body(ctx, stream, body, mail, part);
 
 	if (strncmp(section, "HEADER", 6) == 0 ||
 	    strcmp(section, "MIME") == 0) {
diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/imap/imap-fetch.c
--- a/src/imap/imap-fetch.c	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/imap/imap-fetch.c	Tue Jan 21 07:37:35 2003 +0200
@@ -112,7 +112,8 @@
 	if (o_stream_send_str(ctx->output, str) < 0)
 		return FALSE;
 
-	return message_send(ctx->output, stream, &body_size, 0, (uoff_t)-1);
+	return message_send(ctx->output, stream, &body_size,
+			    0, (uoff_t)-1) >= 0;
 }
 
 static int fetch_send_rfc822_header(struct imap_fetch_context *ctx,
@@ -134,7 +135,7 @@
 	if (o_stream_send_str(ctx->output, str) < 0)
 		return FALSE;
 
-	return message_send(ctx->output, stream, &hdr_size, 0, (uoff_t)-1);
+	return message_send(ctx->output, stream, &hdr_size, 0, (uoff_t)-1) >= 0;
 }
 
 static int fetch_send_rfc822_text(struct imap_fetch_context *ctx,
@@ -157,7 +158,8 @@
 		return FALSE;
 
 	i_stream_seek(stream, hdr_size.physical_size);
-	return message_send(ctx->output, stream, &body_size, 0, (uoff_t)-1);
+	return message_send(ctx->output, stream, &body_size,
+			    0, (uoff_t)-1) >= 0;
 }
 
 static int fetch_mail(struct imap_fetch_context *ctx, struct mail *mail)
@@ -258,6 +260,7 @@
 	ctx.imap_data = imap_data;
 	ctx.bodies = bodies;
 	ctx.output = client->output;
+	ctx.select_counter = client->select_counter;
 	ctx.str = t_str_new(8192);
 
 	ctx.fetch_ctx = client->mailbox->
diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/imap/imap-fetch.h
--- a/src/imap/imap-fetch.h	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/imap/imap-fetch.h	Tue Jan 21 07:37:35 2003 +0200
@@ -28,6 +28,7 @@
 	string_t *str;
 	struct ostream *output;
 	const char *prefix;
+	unsigned int select_counter;
 
 	int first, failed;
 };
diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/lib-mail/message-send.c
--- a/src/lib-mail/message-send.c	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/lib-mail/message-send.c	Tue Jan 21 07:37:35 2003 +0200
@@ -7,18 +7,19 @@
 #include "message-send.h"
 #include "message-size.h"
 
-int message_send(struct ostream *output, struct istream *input,
-		 const struct message_size *msg_size,
-		 uoff_t virtual_skip, uoff_t max_virtual_size)
+off_t message_send(struct ostream *output, struct istream *input,
+		   const struct message_size *msg_size,
+		   uoff_t virtual_skip, uoff_t max_virtual_size)
 {
 	const unsigned char *msg;
 	uoff_t old_limit, limit;
 	size_t i, size;
-	int cr_skipped, add_cr, ret;
+	off_t ret;
+	int cr_skipped, add_cr;
 
 	if (msg_size->physical_size == 0 ||
 	    virtual_skip >= msg_size->virtual_size)
-		return TRUE;
+		return 0;
 
 	if (max_virtual_size > msg_size->virtual_size - virtual_skip)
 		max_virtual_size = msg_size->virtual_size - virtual_skip;
@@ -39,6 +40,7 @@
 	message_skip_virtual(input, virtual_skip, NULL, &cr_skipped);
 
 	/* go through the message data and insert CRs where needed.  */
+	ret = 0;
 	while (max_virtual_size > 0 &&
 	       i_stream_read_data(input, &msg, &size, 0) > 0) {
 		add_cr = FALSE;
@@ -55,12 +57,14 @@
 			}
 		}
 
+		ret += i;
 		if (o_stream_send(output, msg, i) < 0)
-			return FALSE;
+			return -1;
 
 		if (add_cr) {
+			ret++;
 			if (o_stream_send(output, "\r", 1) < 0)
-				return FALSE;
+				return -1;
 			cr_skipped = TRUE;
 		} else {
 			cr_skipped = i > 0 && msg[i-1] == '\r';
@@ -69,5 +73,5 @@
 		i_stream_skip(input, i);
 	}
 
-	return TRUE;
+	return ret;
 }
diff -r 9c8df18fb2a9 -r 21788a1e9e39 src/lib-mail/message-send.h
--- a/src/lib-mail/message-send.h	Tue Jan 21 07:36:32 2003 +0200
+++ b/src/lib-mail/message-send.h	Tue Jan 21 07:37:35 2003 +0200
@@ -6,9 +6,10 @@
 /* Send message to client inserting CRs if needed. Only max_virtual_size
    bytes if sent (relative to virtual_skip), if you want it unlimited,
    use (uoff_t)-1. Remember that if input begins with LF, CR is inserted
-   before it unless virtual_skip = 1. Returns TRUE if successful. */
-int message_send(struct ostream *output, struct istream *input,
-		 const struct message_size *msg_size,
-		 uoff_t virtual_skip, uoff_t max_virtual_size);
+   before it unless virtual_skip = 1. Returns number of bytes sent, or -1
+   if error. */
+off_t message_send(struct ostream *output, struct istream *input,
+		   const struct message_size *msg_size,
+		   uoff_t virtual_skip, uoff_t max_virtual_size);
 
 #endif