perf: speed up job setup, action preparation and the cache server (#1327)

- Look up containers by name instead of listing all of them
- On Linux, cache the docker proxy discovery instead of starting a probe container per job
- Download a job's actions concurrently and share identical fetches between concurrent jobs
- Cache `runner.arch` per run and poll service health every 250ms
- Cache server: queue on an in-process lock instead of polling the database file lock, upload S3 objects up to 64MiB in one request and larger ones in 4 concurrent parts

| `exec`, median of 5 | Before | After |
|---|---:|---:|
| 1 step | 1.70s | 0.87s |
| 10 steps | 2.84s | 1.97s |
| Service + step | 3.78s | 2.18s |
| checkout + Node action | 3.64s | 2.52s |

Reviewed-on: https://gitea.com/gitea/runner/pulls/1327
Reviewed-by: Zettat123 <[email protected]>

act/common/git/fetch_action.go

@@ -16,14 +16,25 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"gitea.com/gitea/runner/act/common"
 )
 
+var actionFetches sync.Map
+
+type actionFetch struct {
+	done     chan struct{}
+	dir, sha string
+	err      error
+	retry    bool // the leader was cancelled or panicked, so followers fetch themselves
+}
+
 var archiveRetryDelay = func(retryAfter string) time.Duration { // as actions/runner backs off
 	if seconds, err := strconv.Atoi(retryAfter); err == nil {
 		return min(max(time.Duration(seconds)*time.Second, 10*time.Second), 10*time.Minute)
@@ -32,6 +43,36 @@ var archiveRetryDelay = func(retryAfter string) time.Duration { // as actions/ru
 }
 
 func FetchAction(ctx context.Context, input NewGitCloneExecutorInput) (string, string, error) { // input.Dir is one clone URL and ref's, holding a directory per commit
+	if !reflect.ValueOf(input).Comparable() {
+		return fetchAction(ctx, input)
+	}
+	for ctx.Err() == nil {
+		call := &actionFetch{done: make(chan struct{}), retry: true}
+		previous, loaded := actionFetches.LoadOrStore(input, call)
+		if !loaded {
+			func() {
+				defer func() { actionFetches.Delete(input); close(call.done) }()
+				call.dir, call.sha, call.err = fetchAction(ctx, input)
+				call.retry = ctx.Err() != nil
+			}()
+			if call.retry {
+				continue
+			}
+			return call.dir, call.sha, call.err
+		}
+		call, _ = previous.(*actionFetch)
+		select {
+		case <-ctx.Done():
+		case <-call.done:
+			if !call.retry && ctx.Err() == nil {
+				return call.dir, call.sha, call.err
+			}
+		}
+	}
+	return "", "", ctx.Err()
+}
+
+func fetchAction(ctx context.Context, input NewGitCloneExecutorInput) (string, string, error) {
 	unlock, err := AcquireCloneLock(ctx, input.Dir)
 	if err != nil {
 		return "", "", err