add PageState.page() to simplify access to page info (#429)

Change-Id: Idd9ccdc105dbc7f7cc37f6a4a49b8715b363b886
apache · Apr 3, 2019 · 768b24f · 768b24f
1 parent c4ca312
commit 768b24f
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Showing 9 changed files with 31 additions and 20 deletions.
diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/serializer/JsonSerializer.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/serializer/JsonSerializer.java
@@ -35,6 +35,7 @@
 import com.baidu.hugegraph.HugeException;
 import com.baidu.hugegraph.api.API;
 import com.baidu.hugegraph.backend.id.Id;
+import com.baidu.hugegraph.backend.page.PageState;
 import com.baidu.hugegraph.backend.store.Shard;
 import com.baidu.hugegraph.iterator.Metadatable;
 import com.baidu.hugegraph.schema.EdgeLabel;
@@ -105,11 +106,10 @@ private String writeIterator(String label, Iterator<?> itor,
                 if (itor instanceof GraphTraversal<?, ?>) {
                     page = TraversalUtil.page((GraphTraversal<?, ?>) itor);
                 } else if (itor instanceof Metadatable) {
-                    page = (String) ((Metadatable) itor).metadata("page");
+                    page = PageState.page(itor);
                 } else {
-                    throw new HugeException(
-                              "Error type '%s' of paging iterator '%s'",
-                              itor.getClass(), itor);
+                    throw new HugeException("Invalid paging iterator: %s",
+                                            itor.getClass());
                 }
                 if (page != null) {
                     page = String.format(",\"page\": \"%s\"", page);

diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/PageEntryIterator.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/PageEntryIterator.java
@@ -72,7 +72,7 @@ private boolean fetch() {
         assert this.results != null;
 
         if (this.results.iterator().hasNext()) {
-            if (results.page() == null) {
+            if (this.results.page() == null) {
                 this.pageState.increase();
             } else {
                 this.pageState.page(this.results.page());
@@ -96,7 +96,7 @@ public BackendEntry next() {
 
     @Override
     public Object metadata(String meta, Object... args) {
-        if ("page".equals(meta)) {
+        if (PageState.PAGE.equals(meta)) {
             if (this.pageState.offset() >= this.queries.total()) {
                 return null;
             }

diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/PageState.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/PageState.java
@@ -20,14 +20,17 @@
 package com.baidu.hugegraph.backend.page;
 
 import java.util.Base64;
+import java.util.Iterator;
 
 import com.baidu.hugegraph.HugeException;
 import com.baidu.hugegraph.backend.serializer.BytesBuffer;
+import com.baidu.hugegraph.iterator.Metadatable;
 import com.baidu.hugegraph.util.Bytes;
 import com.baidu.hugegraph.util.E;
 
 public final class PageState {
 
+    public static final String PAGE = "page";
     public static final String PAGE_NONE = "";
 
     private int offset;
@@ -82,7 +85,7 @@ public static PageState fromString(String page) {
     public static PageState fromBytes(byte[] bytes) {
         if (bytes.length == 0) {
             // The first page
-            return new PageState(0, "");
+            return new PageState(0, PAGE_NONE);
         }
         try {
             BytesBuffer buffer = BytesBuffer.wrap(bytes);
@@ -94,4 +97,11 @@ public static PageState fromBytes(byte[] bytes) {
                                     e, Bytes.toHex(bytes));
         }
     }
+
+    public static String page(Iterator<?> iterator) {
+        E.checkState(iterator instanceof Metadatable,
+                     "Invalid paging iterator: %s", iterator.getClass());
+        Object page = ((Metadatable) iterator).metadata(PAGE);
+        return (String) page;
+    }
 }
diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/QueryList.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/page/QueryList.java
@@ -185,10 +185,10 @@ public PageIterator iterator(int index, String page, long pageSize) {
             assert index == 0;
             this.query.page(page);
             Iterator<BackendEntry> iterator = fetcher.apply(this.query);
-            // Must iterate all entries before get the next page
+            // Must iterate all entries before getting the next page info
             List<BackendEntry> results = IteratorUtils.list(iterator);
-            page = (String) ((Metadatable) iterator).metadata("page");
-            return new PageIterator(results.iterator(), page);
+            return new PageIterator(results.iterator(),
+                                    PageState.page(iterator));
         }
 
         public int total() {

diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/store/BackendEntryIterator.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/store/BackendEntryIterator.java
@@ -22,6 +22,7 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
+import com.baidu.hugegraph.backend.page.PageState;
 import com.baidu.hugegraph.backend.query.Query;
 import com.baidu.hugegraph.exception.LimitExceedException;
 import com.baidu.hugegraph.exception.NotSupportException;
@@ -81,7 +82,7 @@ public BackendEntry next() {
 
     @Override
     public Object metadata(String meta, Object... args) {
-        if ("page".equals(meta)) {
+        if (PageState.PAGE.equals(meta)) {
             return this.pageState();
         }
         throw new NotSupportException("Invalid meta '%s'", meta);

diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/tx/GraphIndexTransaction.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/backend/tx/GraphIndexTransaction.java
@@ -43,6 +43,7 @@
 import com.baidu.hugegraph.backend.page.IdHolder;
 import com.baidu.hugegraph.backend.page.IdHolderList;
 import com.baidu.hugegraph.backend.page.PageIds;
+import com.baidu.hugegraph.backend.page.PageState;
 import com.baidu.hugegraph.backend.query.Condition;
 import com.baidu.hugegraph.backend.query.Condition.Relation;
 import com.baidu.hugegraph.backend.query.ConditionQuery;
@@ -486,8 +487,7 @@ private PageIds doIndexQueryOnce(IndexLabel indexLabel,
                          "The entries must be Metadatable when query " +
                          "in paging, but got '%s'",
                          entries.getClass().getName());
-            Object page = ((Metadatable) entries).metadata("page");
-            return new PageIds(ids, (String) page);
+            return new PageIds(ids, PageState.page(entries));
         } finally {
             locks.unlock();
         }

diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/optimize/TraversalUtil.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/optimize/TraversalUtil.java
@@ -55,6 +55,7 @@
 import com.baidu.hugegraph.HugeGraph;
 import com.baidu.hugegraph.backend.BackendException;
 import com.baidu.hugegraph.backend.id.Id;
+import com.baidu.hugegraph.backend.page.PageState;
 import com.baidu.hugegraph.backend.query.Condition;
 import com.baidu.hugegraph.backend.query.Condition.Relation;
 import com.baidu.hugegraph.backend.query.Condition.RelationType;
@@ -587,14 +588,15 @@ public static void retriveSysprop(List<HasContainer> hasContainers,
 
     public static String page(GraphTraversal<?, ?> traversal) {
         QueryHolder holder = rootStep(traversal);
-        E.checkState(holder != null, "Invalid traversal: %s", traversal);
-        return (String) holder.metadata("page");
+        E.checkState(holder != null,
+                     "Invalid paging traversal: %s", traversal.getClass());
+        return (String) holder.metadata(PageState.PAGE);
     }
 
     public static QueryHolder rootStep(GraphTraversal<?, ?> traversal) {
         for (final Step<?, ?> step : traversal.asAdmin().getSteps()) {
             if (step instanceof QueryHolder) {
-                return ((QueryHolder) step);
+                return (QueryHolder) step;
             }
         }
         return null;

diff --git a/hugegraph-test/src/main/java/com/baidu/hugegraph/core/EdgeCoreTest.java b/hugegraph-test/src/main/java/com/baidu/hugegraph/core/EdgeCoreTest.java
@@ -53,7 +53,6 @@
 import com.baidu.hugegraph.config.CoreOptions;
 import com.baidu.hugegraph.exception.LimitExceedException;
 import com.baidu.hugegraph.exception.NotFoundException;
-import com.baidu.hugegraph.iterator.Metadatable;
 import com.baidu.hugegraph.schema.SchemaManager;
 import com.baidu.hugegraph.testutil.Assert;
 import com.baidu.hugegraph.testutil.FakeObjects.FakeEdge;
@@ -1769,7 +1768,7 @@ public void testScanEdgeInPaging() {
             while (iterator.hasNext()) {
                 edges.add(iterator.next());
             }
-            page = (String) ((Metadatable) iterator).metadata("page");
+            page = PageState.page(iterator);
         }
         Assert.assertEquals(18, edges.size());
     }

diff --git a/hugegraph-test/src/main/java/com/baidu/hugegraph/core/VertexCoreTest.java b/hugegraph-test/src/main/java/com/baidu/hugegraph/core/VertexCoreTest.java
@@ -53,7 +53,6 @@
 import com.baidu.hugegraph.backend.store.Shard;
 import com.baidu.hugegraph.backend.tx.GraphTransaction;
 import com.baidu.hugegraph.exception.NoIndexException;
-import com.baidu.hugegraph.iterator.Metadatable;
 import com.baidu.hugegraph.schema.PropertyKey;
 import com.baidu.hugegraph.schema.SchemaManager;
 import com.baidu.hugegraph.schema.VertexLabel;
@@ -3031,7 +3030,7 @@ public void testScanVertexInPaging() {
             while (iterator.hasNext()) {
                 vertexes.add(iterator.next());
             }
-            page = (String) ((Metadatable) iterator).metadata("page");
+            page = PageState.page(iterator);
         }
         Assert.assertEquals(10, vertexes.size());
     }