Fix deadlock in memrevcache (#1895)

The current memrevcache code will deadlock on Insert, every time: Insert
takes the write lock at the top, and later calls Get, which tries to get
the read lock. This is an automatic deadlock.

Also:
- Fix some log identifiers in go PS handlers.

go/lib/revcache/memrevcache/memrevcache.go

@@ -42,7 +42,11 @@ func New(defaultExpiration, cleanupInterval time.Duration) revcache.RevCache {
 func (c *memRevCache) Get(k *revcache.Key) (*path_mgmt.SignedRevInfo, bool) {
 	c.lock.RLock()
 	defer c.lock.RUnlock()
-	obj, ok := c.c.Get(k.String())
+	return c.get(k.String())
+}
+
+func (c *memRevCache) get(key string) (*path_mgmt.SignedRevInfo, bool) {
+	obj, ok := c.c.Get(key)
 	if !ok {
 		return nil, false
 	}
@@ -62,7 +66,7 @@ func (c *memRevCache) Insert(rev *path_mgmt.SignedRevInfo) bool {
 	}
 	k := revcache.NewKey(newInfo.IA(), newInfo.IfID)
 	key := k.String()
-	val, ok := c.Get(k)
+	val, ok := c.get(key)
 	if !ok {
 		c.c.Set(key, rev, ttl)
 		return true

go/path_srv/internal/handlers/segreqcore.go

@@ -78,7 +78,7 @@ func (h *segReqCoreHandler) handleReq(ctx context.Context,
 	}
 	dstCore, err := h.isCoreDst(ctx, msger, segReq)
 	if err != nil {
-		h.logger.Error("[segReqHandler] Failed to determine dest type", "err", err)
+		h.logger.Error("[segReqCoreHandler] Failed to determine dest type", "err", err)
 		h.sendEmptySegReply(ctx, segReq, msger)
 		return
 	}
@@ -98,7 +98,7 @@ func (h *segReqCoreHandler) handleReq(ctx context.Context,
 		return
 	}
 	if len(downSegs) == 0 {
-		h.logger.Debug("[segReqHandler] no down segs found")
+		h.logger.Debug("[segReqCoreHandler] no down segs found")
 		h.sendEmptySegReply(ctx, segReq, msger)
 		return
 	}
@@ -118,7 +118,7 @@ func (h *segReqCoreHandler) handleReq(ctx context.Context,
 			retry := len(ias) == len(downIAs) && !segReq.Flags.CacheOnly
 			coreSegs, err = h.fetchCoreSegsFromDB(ctx, downIAs, retry)
 			if err != nil {
-				h.logger.Error("[segReqHandler] Failed to find core segs", "err", err)
+				h.logger.Error("[segReqCoreHandler] Failed to find core segs", "err", err)
 				h.sendEmptySegReply(ctx, segReq, msger)
 				return
 			}
@@ -133,7 +133,7 @@ func (h *segReqCoreHandler) handleReq(ctx context.Context,
 			return coreExists
 		})
 	}
-	h.logger.Debug("[segReqHandler] found segs", "core", len(coreSegs), "down", len(downSegs))
+	h.logger.Debug("[segReqCoreHandler] found segs", "core", len(coreSegs), "down", len(downSegs))
 	h.sendReply(ctx, msger, nil, coreSegs, downSegs, segReq)
 }