[refactor](SimpleScheduler) refactor code for getting available backe…

…nd in SimpleScheduler (apache#12710)
FreeOnePlus · Oct 8, 2022 · 93c7805 · 93c7805
1 parent 3b3b555
commit 93c7805
Showing 1 changed file with 11 additions and 39 deletions.
diff --git a/fe/fe-core/src/main/java/org/apache/doris/qe/SimpleScheduler.java b/fe/fe-core/src/main/java/org/apache/doris/qe/SimpleScheduler.java
@@ -126,38 +126,17 @@ public static TScanRangeLocation getLocation(TScanRangeLocation minLocation,
     public static TNetworkAddress getHost(ImmutableMap<Long, Backend> backends,
                                           Reference<Long> backendIdRef)
             throws UserException {
-        if (backends == null || backends.isEmpty()) {
-            throw new UserException("candidate backends is empty");
+        long id = nextId.getAndIncrement() % backends.size();
+        Map.Entry<Long, Backend> backendEntry = backends.entrySet().stream().skip(id).filter(
+                e -> isAvailable(e.getValue())).findFirst().orElse(null);
+        if (backendEntry == null && id > 0) {
+            backendEntry = backends.entrySet().stream().filter(
+                e -> isAvailable(e.getValue())).limit(id).findFirst().orElse(null);
         }
-        int backendSize = backends.size();
-        long id = nextId.getAndIncrement() % backendSize;
-
-        List<Long> idToBackendId = Lists.newArrayList();
-        idToBackendId.addAll(backends.keySet());
-        Long backendId = idToBackendId.get((int) id);
-        Backend backend = backends.get(backendId);
-
-        if (isAvailable(backend)) {
-            backendIdRef.setRef(backendId);
+        if (backendEntry != null) {
+            Backend backend = backendEntry.getValue();
+            backendIdRef.setRef(backendEntry.getKey());
             return new TNetworkAddress(backend.getHost(), backend.getBePort());
-        } else {
-            long candidateId = id + 1;  // get next candidate id
-            for (int i = 0; i < backendSize; i++, candidateId++) {
-                LOG.debug("i={} candidatedId={}", i, candidateId);
-                if (candidateId >= backendSize) {
-                    candidateId = 0;
-                }
-                if (candidateId == id) {
-                    continue;
-                }
-                Long candidatebackendId = idToBackendId.get((int) candidateId);
-                LOG.debug("candidatebackendId={}", candidatebackendId);
-                Backend candidateBackend = backends.get(candidatebackendId);
-                if (isAvailable(candidateBackend)) {
-                    backendIdRef.setRef(candidatebackendId);
-                    return new TNetworkAddress(candidateBackend.getHost(), candidateBackend.getBePort());
-                }
-            }
         }
         // no backend returned
         throw new UserException(SystemInfoService.NO_SCAN_NODE_BACKEND_AVAILABLE_MSG
@@ -253,14 +232,7 @@ public void run() {
     }
 
     public static TNetworkAddress getHostByCurrentBackend(Map<TNetworkAddress, Long> addressToBackendID) {
-        int backendSize = addressToBackendID.size();
-        if (backendSize == 0) {
-            return null;
-        }
-        Long id = nextId.getAndIncrement() % backendSize;
-
-        List<TNetworkAddress> idToBackendId = Lists.newArrayList();
-        idToBackendId.addAll(addressToBackendID.keySet());
-        return idToBackendId.get(id.intValue());
+        long id = nextId.getAndIncrement() % addressToBackendID.size();
+        return addressToBackendID.keySet().stream().skip(id).findFirst().orElse(null);
     }
 }