From 5525452bdf517227e1e6f92fc4adde5f45b4d858 Mon Sep 17 00:00:00 2001
From: guillep2k <18600385+guillep2k@users.noreply.github.com>
Date: Sat, 15 Feb 2020 14:07:09 -0300
Subject: [PATCH] Divide GetIssueStats query in smaller chunks (#10176)
 (#10282)

* Divide GetIssueStats query in smaller chunks

* Skip chunking if count is low enough

* Fix lint

* Define maxQueryParameters

* Remove absMaxQueryParameters because of lint

* Restart CI

* Restart CI

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
---
 models/issue.go  | 30 ++++++++++++++++++++++++++++++
 models/models.go |  6 ++++++
 2 files changed, 36 insertions(+)

diff --git a/models/issue.go b/models/issue.go
index 7c7a7c295ad..5d6c9a83e2e 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -1336,6 +1336,36 @@ type IssueStatsOptions struct {
 
 // GetIssueStats returns issue statistic information by given conditions.
 func GetIssueStats(opts *IssueStatsOptions) (*IssueStats, error) {
+	if len(opts.IssueIDs) <= maxQueryParameters {
+		return getIssueStatsChunk(opts, opts.IssueIDs)
+	}
+
+	// If too long a list of IDs is provided, we get the statistics in
+	// smaller chunks and get accumulates. Note: this could potentially
+	// get us invalid results. The alternative is to insert the list of
+	// ids in a temporary table and join from them.
+	accum := &IssueStats{}
+	for i := 0; i < len(opts.IssueIDs); {
+		chunk := i + maxQueryParameters
+		if chunk > len(opts.IssueIDs) {
+			chunk = len(opts.IssueIDs)
+		}
+		stats, err := getIssueStatsChunk(opts, opts.IssueIDs[i:chunk])
+		if err != nil {
+			return nil, err
+		}
+		accum.OpenCount += stats.OpenCount
+		accum.ClosedCount += stats.ClosedCount
+		accum.YourRepositoriesCount += stats.YourRepositoriesCount
+		accum.AssignCount += stats.AssignCount
+		accum.CreateCount += stats.CreateCount
+		accum.OpenCount += stats.MentionCount
+		i = chunk
+	}
+	return accum, nil
+}
+
+func getIssueStatsChunk(opts *IssueStatsOptions, issueIDs []int64) (*IssueStats, error) {
 	stats := &IssueStats{}
 
 	countSession := func(opts *IssueStatsOptions) *xorm.Session {
diff --git a/models/models.go b/models/models.go
index 9eb174e200d..fa578403820 100644
--- a/models/models.go
+++ b/models/models.go
@@ -46,6 +46,12 @@ type Engine interface {
 	Asc(colNames ...string) *xorm.Session
 }
 
+const (
+	// When queries are broken down in parts because of the number
+	// of parameters, attempt to break by this amount
+	maxQueryParameters = 300
+)
+
 var (
 	x      *xorm.Engine
 	tables []interface{}