Bug 897074 - Limit the number of tokens used in satchel's getAutoCompleteResults SQL queries. r=dolske

toolkit/components/satchel/FormHistory.jsm

@@ -98,6 +98,7 @@ XPCOMUtils.defineLazyServiceGetter(this, "uuidService",
 
 const DB_SCHEMA_VERSION = 4;
 const DAY_IN_MS  = 86400000; // 1 day in milliseconds
+const MAX_SEARCH_TOKENS = 30;
 const NOOP = function noop() {};
 
 let supportsDeletedTable =
@@ -969,7 +970,8 @@ this.FormHistory = {
         // for each word, calculate word boundary weights for the SELECT clause and
         // add word to the WHERE clause of the query
         let tokenCalc = [];
-        for (let i = 0; i < searchTokens.length; i++) {
+        let searchTokenCount = Math.min(searchTokens.length, MAX_SEARCH_TOKENS);
+        for (let i = 0; i < searchTokenCount; i++) {
             tokenCalc.push("(value LIKE :tokenBegin" + i + " ESCAPE '/') + " +
                             "(value LIKE :tokenBoundary" + i + " ESCAPE '/')");
             where += "AND (value LIKE :tokenContains" + i + " ESCAPE '/') ";
@@ -1021,7 +1023,8 @@ this.FormHistory = {
     if (searchString.length >= 1)
       stmt.params.valuePrefix = stmt.escapeStringForLIKE(searchString, "/") + "%";
     if (searchString.length > 1) {
-      for (let i = 0; i < searchTokens.length; i++) {
+      let searchTokenCount = Math.min(searchTokens.length, MAX_SEARCH_TOKENS);
+      for (let i = 0; i < searchTokenCount; i++) {
         let escapedToken = stmt.escapeStringForLIKE(searchTokens[i], "/");
         stmt.params["tokenBegin" + i] = escapedToken + "%";
         stmt.params["tokenBoundary" + i] =  "% " + escapedToken + "%";

toolkit/components/satchel/test/unit/test_autocomplete.js

@@ -2,6 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+"use strict";
+
 var testnum = 0;
 var fac;
 var prefs;
@@ -235,3 +237,46 @@ add_test(function test13() {
   do_check_eq(results.getValueAt(1), "sync1a");
   run_next_test();
 });
+
+add_test(function test_token_limit_DB() {
+    function test_token_limit_previousResult(previousResult) {
+        do_log_info("Check that the number of tokens used in a search is not capped to " +
+                    "MAX_SEARCH_TOKENS when using a previousResult");
+        // This provide more accuracy since performance is less of an issue.
+        let changes = [ ];
+        // Search for a string where the first 30 tokens match the value above but the 31st does not
+        // when re-using a previous result.
+        fac.autoCompleteSearchAsync("field_token_cap",
+                                    "a b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 .",
+                                    null, previousResult, {
+                                        onSearchCompletion : function(aResults) {
+                                            do_check_eq(aResults.matchCount, 0,
+                                                        "All search tokens should be used with " +
+                                                        "previous results");
+                                            run_next_test();
+                                        }
+                                    });
+    }
+
+    do_log_info("Check that the number of tokens used in a search is capped to MAX_SEARCH_TOKENS " +
+                "for performance when querying the DB");
+    let changes = [ ];
+    changes.push({ op : "add", fieldname: "field_token_cap",
+                   // value with 36 unique tokens
+                   value: "a b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 0",
+                   timesUsed: 1, firstUsed: 0, lastUsed: 0 });
+    updateFormHistory(changes, () => {
+        // Search for a string where the first 30 tokens match the value above but the 31st does not
+        // (which would prevent the result from being returned if the 31st term was used).
+        fac.autoCompleteSearchAsync("field_token_cap",
+                                    "a b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 .",
+                                    null, null, {
+                                        onSearchCompletion : function(aResults) {
+                                            do_check_eq(aResults.matchCount, 1,
+                                                        "Only the first MAX_SEARCH_TOKENS tokens " +
+                                                        "should be used for DB queries");
+                                            test_token_limit_previousResult(aResults);
+                                        }
+        });
+    });
+});