[MM-53968] Includes mattermost-plugin-api into the mono repo (#24235)

Include https://github.com/mattermost/mattermost-plugin-api into the mono repo

Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>
Co-authored-by: Michael Kochell <mjkochell@gmail.com>
Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>
Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>
Co-authored-by: Alex Dovenmuehle <alex.dovenmuehle@mattermost.com>
Co-authored-by: Michael Kochell <6913320+mickmister@users.noreply.github.com>
Co-authored-by: Christopher Poile <cpoile@gmail.com>
Co-authored-by: İlker Göktuğ Öztürk <ilkergoktugozturk@gmail.com>
Co-authored-by: Shota Gvinepadze <wineson@gmail.com>
Co-authored-by: Ali Farooq <ali.farooq0@pm.me>
Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>
Co-authored-by: Daniel Espino García <larkox@gmail.com>
Co-authored-by: Christopher Speller <crspeller@gmail.com>
Co-authored-by: Alex Dovenmuehle <adovenmuehle@gmail.com>
Co-authored-by: Szymon Gibała <szymongib@gmail.com>
Co-authored-by: Lev <1187448+levb@users.noreply.github.com>
Co-authored-by: Jason Frerich <jason.frerich@mattermost.com>
Co-authored-by: Agniva De Sarker <agnivade@yahoo.co.in>
Co-authored-by: Artur M. Wolff <artur.m.wolff@gmail.com>
Co-authored-by: Madhav Hugar <16546715+madhavhugar@users.noreply.github.com>
Co-authored-by: Joe <security.joe@pm.me>
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
Co-authored-by: José Peso <trilopin@users.noreply.github.com>

server/public/pluginapi/cluster/job_once_mem_test.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package cluster
+
+import (
+	"fmt"
+	"runtime"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/mattermost/mattermost/server/public/model"
+)
+
+func TestMemFootprint(t *testing.T) {
+	var memConsumed = func() uint64 {
+		runtime.GC()
+		var s runtime.MemStats
+		runtime.ReadMemStats(&s)
+		return s.Sys
+	}
+
+	t.Run("average k per jobOnce", func(t *testing.T) {
+		t.SkipNow()
+
+		makeKey := model.NewId
+
+		numJobs := 100000
+		jobs := make(map[string]*int32, numJobs)
+		for i := 0; i < numJobs; i++ {
+			jobs[makeKey()] = new(int32)
+		}
+
+		callback := func(key string, _ any) {
+			count, ok := jobs[key]
+			if ok {
+				atomic.AddInt32(count, 1)
+			}
+		}
+
+		mockPluginAPI := newMockPluginAPI(t)
+		s := GetJobOnceScheduler(mockPluginAPI)
+		err := s.SetCallback(callback)
+		require.NoError(t, err)
+		err = s.Start()
+		require.NoError(t, err)
+
+		getVal := func(key string) []byte {
+			data, _ := s.pluginAPI.KVGet(key)
+			return data
+		}
+
+		before := memConsumed()
+
+		for k := range jobs {
+			assert.Empty(t, getVal(oncePrefix+k))
+			_, err = s.ScheduleOnce(k, time.Now().Add(5*time.Minute), nil)
+			require.NoError(t, err)
+			assert.NotEmpty(t, getVal(oncePrefix+k))
+		}
+
+		time.Sleep(10 * time.Second)
+
+		// Everything scheduled now:
+		s.activeJobs.mu.RLock()
+		assert.Equal(t, numJobs, len(s.activeJobs.jobs))
+		s.activeJobs.mu.RUnlock()
+		list, err := s.ListScheduledJobs()
+		require.NoError(t, err)
+		assert.Equal(t, numJobs, len(list))
+
+		after := memConsumed()
+
+		fmt.Printf("\nthe %d jobs, scheduler, and goroutines require: %.2fmB memory, or %.3fkB each job\n",
+			numJobs,
+			float64(after-before)/(1024*1024),
+			(float64(after-before)/float64(numJobs))/1024)
+	})
+}