From: Timo Sirainen <timo.sirainen@dovecot.fi>
Date: Sun, 16 Oct 2016 19:40:18 +0000 (+0300)
Subject: lib-dict: Added dict_iterate_set_limit()
X-Git-Tag: 2.2.26~117
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1b69afd91e9b38b935190c5683e9f83a189c68aa;p=thirdparty%2Fdovecot%2Fcore.git

lib-dict: Added dict_iterate_set_limit()
---

diff --git a/src/lib-dict/dict-private.h b/src/lib-dict/dict-private.h
index 43d768d87d..2abb80dc91 100644
--- a/src/lib-dict/dict-private.h
+++ b/src/lib-dict/dict-private.h
@@ -54,6 +54,7 @@ struct dict_iterate_context {
 	void *async_context;
 
 	unsigned int has_more:1;
+	uint64_t row_count, max_rows;
 };
 
 struct dict_transaction_context {
diff --git a/src/lib-dict/dict.c b/src/lib-dict/dict.c
index 5b775396af..92d5570883 100644
--- a/src/lib-dict/dict.c
+++ b/src/lib-dict/dict.c
@@ -175,8 +175,16 @@ dict_iterate_init_multiple(struct dict *dict, const char *const *paths,
 bool dict_iterate(struct dict_iterate_context *ctx,
 		  const char **key_r, const char **value_r)
 {
-	return ctx == &dict_iter_unsupported ? FALSE :
-		ctx->dict->v.iterate(ctx, key_r, value_r);
+	if (ctx == &dict_iter_unsupported)
+		return FALSE;
+	if (ctx->max_rows > 0 && ctx->row_count >= ctx->max_rows) {
+		/* row count was limited */
+		return FALSE;
+	}
+	if (!ctx->dict->v.iterate(ctx, key_r, value_r))
+		return FALSE;
+	ctx->row_count++;
+	return TRUE;
 }
 
 void dict_iterate_set_async_callback(struct dict_iterate_context *ctx,
@@ -187,6 +195,12 @@ void dict_iterate_set_async_callback(struct dict_iterate_context *ctx,
 	ctx->async_context = context;
 }
 
+void dict_iterate_set_limit(struct dict_iterate_context *ctx,
+			    uint64_t max_rows)
+{
+	ctx->max_rows = max_rows;
+}
+
 bool dict_iterate_has_more(struct dict_iterate_context *ctx)
 {
 	return ctx->has_more;
diff --git a/src/lib-dict/dict.h b/src/lib-dict/dict.h
index 150834dba5..69e213d41c 100644
--- a/src/lib-dict/dict.h
+++ b/src/lib-dict/dict.h
@@ -107,6 +107,10 @@ dict_iterate_init_multiple(struct dict *dict, const char *const *paths,
 void dict_iterate_set_async_callback(struct dict_iterate_context *ctx,
 				     dict_iterate_callback_t *callback,
 				     void *context);
+/* Limit how many rows will be returned by the iteration (0 = unlimited).
+   This allows backends to optimize the query (e.g. use LIMIT 1 with SQL). */
+void dict_iterate_set_limit(struct dict_iterate_context *ctx,
+			    uint64_t max_rows);
 /* If dict_iterate() returns FALSE, the iteration may be finished or if this
    is an async iteration it may be waiting for more data. If this function
    returns TRUE, the dict callback is called again with more data. */