{"action":"created","comment":{"url":"https://api.github.com/repos/dotnet/corefx/pulls/comments/61692798","id":61692798,"diff_hunk":"@@ -36,25 +54,43 @@ private unsafe string GetAsciiCore(char* unicode, int count)\n         private unsafe string GetUnicodeCore(char* ascii, int count)\n         {\n             uint flags = Flags;\n-            CheckInvalidIdnCharacters(ascii, count, flags, \"ascii\");\n+            CheckInvalidIdnCharacters(ascii, count, flags, nameof(ascii));\n \n-            char[] buf = new char[count];\n-\n-            for (int attempts = 2; attempts > 0; attempts--)\n+            const int StackAllocThreshold = 512;\n+            if (count < StackAllocThreshold)\n             {\n-                int realLen = Interop.GlobalizationNative.ToUnicode(flags, ascii, count, buf, buf.Length);\n-\n-                if (realLen == 0)\n+                char* output = stackalloc char[count];\n+                return GetUnicodeCore(ascii, count, flags, output, count, reattempt: true);\n+            }\n+            else\n+            {\n+                char[] output = new char[count];\n+                fixed (char* pOutput = output)\n                 {\n-                    break;\n+                    return GetUnicodeCore(ascii, count, flags, pOutput, count, reattempt: true);\n                 }\n+            }\n+        }\n+\n+        private unsafe string GetUnicodeCore(char* ascii, int count, uint flags, char* output, int outputLength, bool reattempt)\n+        {\n+            int realLen = Interop.GlobalizationNative.ToUnicode(fascii, count, flags, output, outputLength);","path":"src/Common/src/System/Globalization/IdnMapping.Unix.cs","position":88,"original_position":88,"commit_id":"78cd5a70bcd83c9320e8e8758d7f4d573b97ad96","original_commit_id":"78cd5a70bcd83c9320e8e8758d7f4d573b97ad96","user":{"login":"stephentoub","id":2642209,"avatar_url":"https://avatars.githubusercontent.com/u/2642209?v=3","gravatar_id":"","url":"https://api.github.com/users/stephentoub","html_url":"https://github.com/stephentoub","followers_url":"https://api.github.com/users/stephentoub/followers","following_url":"https://api.github.com/users/stephentoub/following{/other_user}","gists_url":"https://api.github.com/users/stephentoub/gists{/gist_id}","starred_url":"https://api.github.com/users/stephentoub/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/stephentoub/subscriptions","organizations_url":"https://api.github.com/users/stephentoub/orgs","repos_url":"https://api.github.com/users/stephentoub/repos","events_url":"https://api.github.com/users/stephentoub/events{/privacy}","received_events_url":"https://api.github.com/users/stephentoub/received_events","type":"User","site_admin":false},"body":"Ditto.  And ```fascii`` is a misspelled variable name.","created_at":"2016-05-01T20:45:49Z","updated_at":"2016-05-01T20:45:49Z","html_url":"https://github.com/dotnet/corefx/pull/8197#discussion_r61692798","pull_request_url":"https://api.github.com/repos/dotnet/corefx/pulls/8197","_links":{"self":{"href":"https://api.github.com/repos/dotnet/corefx/pulls/comments/61692798"},"html":{"href":"https://github.com/dotnet/corefx/pull/8197#discussion_r61692798"},"pull_request":{"href":"https://api.github.com/repos/dotnet/corefx/pulls/8197"}}},"pull_request":{"url":"https://api.github.com/repos/dotnet/corefx/pulls/8197","id":68465825,"html_url":"https://github.com/dotnet/corefx/pull/8197","diff_url":"https://github.com/dotnet/corefx/pull/8197.diff","patch_url":"https://github.com/dotnet/corefx/pull/8197.patch","issue_url":"https://api.github.com/repos/dotnet/corefx/issues/8197","number":8197,"state":"open","locked":false,"title":"Improve performance of IdnMapping","user":{"login":"hughbe","id":1275900,"avatar_url":"https://avatars.githubusercontent.com/u/1275900?v=3","gravatar_id":"","url":"https://api.github.com/users/hughbe","html_url":"https://github.com/hughbe","followers_url":"https://api.github.com/users/hughbe/followers","following_url":"https://api.github.com/users/hughbe/following{/other_user}","gists_url":"https://api.github.com/users/hughbe/gists{/gist_id}","starred_url":"https://api.github.com/users/hughbe/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hughbe/subscriptions","organizations_url":"https://api.github.com/users/hughbe/orgs","repos_url":"https://api.github.com/users/hughbe/repos","events_url":"https://api.github.com/users/hughbe/events{/privacy}","received_events_url":"https://api.github.com/users/hughbe/received_events","type":"User","site_admin":false},"body":"- Use stack allocation when the length is relatively short\r\n- The interop methods can take char*\r\n\r\nSimilar change to @stephentoub's BitConverter.ToString work in #7269 \r\n\r\n/cc @ellismg @stephentoub @tarekgh @jamesqo","created_at":"2016-04-30T11:39:06Z","updated_at":"2016-05-01T20:45:49Z","closed_at":null,"merged_at":null,"merge_commit_sha":"f0a8f8723e658db90dc03a58b34d05aa4fc9b671","assignee":null,"milestone":null,"commits_url":"https://api.github.com/repos/dotnet/corefx/pulls/8197/commits","review_comments_url":"https://api.github.com/repos/dotnet/corefx/pulls/8197/comments","review_comment_url":"https://api.github.com/repos/dotnet/corefx/pulls/comments{/number}","comments_url":"https://api.github.com/repos/dotnet/corefx/issues/8197/comments","statuses_url":"https://api.github.com/repos/dotnet/corefx/statuses/78cd5a70bcd83c9320e8e8758d7f4d573b97ad96","head":{"label":"hughbe:idnmapping-stack","ref":"idnmapping-stack","sha":"78cd5a70bcd83c9320e8e8758d7f4d573b97ad96","user":{"login":"hughbe","id":1275900,"avatar_url":"https://avatars.githubusercontent.com/u/1275900?v=3","gravatar_id":"","url":"https://api.github.com/users/hughbe","html_url":"https://github.com/hughbe","followers_url":"https://api.github.com/users/hughbe/followers","following_url":"https://api.github.com/users/hughbe/following{/other_user}","gists_url":"https://api.github.com/users/hughbe/gists{/gist_id}","starred_url":"https://api.github.com/users/hughbe/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hughbe/subscriptions","organizations_url":"https://api.github.com/users/hughbe/orgs","repos_url":"https://api.github.com/users/hughbe/repos","events_url":"https://api.github.com/users/hughbe/events{/privacy}","received_events_url":"https://api.github.com/users/hughbe/received_events","type":"User","site_admin":false},"repo":{"id":47085914,"name":"corefx","full_name":"hughbe/corefx","owner":{"login":"hughbe","id":1275900,"avatar_url":"https://avatars.githubusercontent.com/u/1275900?v=3","gravatar_id":"","url":"https://api.github.com/users/hughbe","html_url":"https://github.com/hughbe","followers_url":"https://api.github.com/users/hughbe/followers","following_url":"https://api.github.com/users/hughbe/following{/other_user}","gists_url":"https://api.github.com/users/hughbe/gists{/gist_id}","starred_url":"https://api.github.com/users/hughbe/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hughbe/subscriptions","organizations_url":"https://api.github.com/users/hughbe/orgs","repos_url":"https://api.github.com/users/hughbe/repos","events_url":"https://api.github.com/users/hughbe/events{/privacy}","received_events_url":"https://api.github.com/users/hughbe/received_events","type":"User","site_admin":false},"private":false,"html_url":"https://github.com/hughbe/corefx","description":"This repo contains the .NET Core foundational libraries, called CoreFX. 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