Multiple bookmarks #376
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| /* | ||
| * Copyright (c) 2002-2017 "Neo Technology," | ||
| * Network Engine for Objects in Lund AB [http://neotechnology.com] | ||
| * | ||
| * This file is part of Neo4j. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package org.neo4j.driver.internal; | ||
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| import java.util.Collections; | ||
| import java.util.HashMap; | ||
| import java.util.Iterator; | ||
| import java.util.Map; | ||
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| import org.neo4j.driver.v1.Value; | ||
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| import static java.util.Collections.emptyMap; | ||
| import static java.util.Collections.singleton; | ||
| import static org.neo4j.driver.v1.Values.value; | ||
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| public final class Bookmark | ||
| { | ||
| private static final String BOOKMARK_KEY = "bookmark"; | ||
| private static final String BOOKMARKS_KEY = "bookmarks"; | ||
| private static final String BOOKMARK_PREFIX = "neo4j:bookmark:v1:tx"; | ||
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| private static final long UNKNOWN_BOOKMARK_VALUE = -1; | ||
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| private static final Bookmark EMPTY = new Bookmark( Collections.<String>emptySet() ); | ||
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| private final Iterable<String> values; | ||
| private final String maxValue; | ||
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| private Bookmark( Iterable<String> values ) | ||
| { | ||
| this.values = values; | ||
| this.maxValue = maxBookmark( values ); | ||
| } | ||
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| public static Bookmark empty() | ||
| { | ||
| return EMPTY; | ||
| } | ||
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| public static Bookmark from( String value ) | ||
| { | ||
| if ( value == null ) | ||
| { | ||
| return empty(); | ||
| } | ||
| return from( singleton( value ) ); | ||
| } | ||
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| public static Bookmark from( Iterable<String> values ) | ||
| { | ||
| if ( values == null ) | ||
| { | ||
| return empty(); | ||
| } | ||
| return new Bookmark( values ); | ||
| } | ||
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| public boolean isEmpty() | ||
| { | ||
| return maxValue == null; | ||
| } | ||
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| public String asString() | ||
| { | ||
| return maxValue; | ||
| } | ||
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| public Map<String,Value> asParameters() | ||
|
There was a problem hiding this comment. maybe |
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| { | ||
| if ( isEmpty() ) | ||
| { | ||
| return emptyMap(); | ||
| } | ||
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| // Driver sends {bookmark: "max", bookmarks: ["one", "two", "max"]} instead of simple | ||
| // {bookmarks: ["one", "two", "max"]} for backwards compatibility reasons. Old servers can only accept single | ||
| // bookmark that is why driver has to parse and compare given list of bookmarks. This functionality will | ||
| // eventually be removed. | ||
| Map<String,Value> parameters = new HashMap<>( 4 ); | ||
| parameters.put( BOOKMARK_KEY, value( maxValue ) ); | ||
| parameters.put( BOOKMARKS_KEY, value( values ) ); | ||
| return parameters; | ||
| } | ||
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| @Override | ||
| public String toString() | ||
| { | ||
| return "Bookmark{values=" + values + "}"; | ||
| } | ||
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| private static String maxBookmark( Iterable<String> bookmarks ) | ||
| { | ||
| if ( bookmarks == null ) | ||
| { | ||
| return null; | ||
| } | ||
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| Iterator<String> iterator = bookmarks.iterator(); | ||
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| if ( !iterator.hasNext() ) | ||
| { | ||
| return null; | ||
| } | ||
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| String maxBookmark = iterator.next(); | ||
| long maxValue = bookmarkValue( maxBookmark ); | ||
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| while ( iterator.hasNext() ) | ||
| { | ||
| String bookmark = iterator.next(); | ||
| long value = bookmarkValue( bookmark ); | ||
|
There was a problem hiding this comment. value might be null for the following case: |
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| if ( value > maxValue ) | ||
| { | ||
| maxBookmark = bookmark; | ||
| maxValue = value; | ||
| } | ||
| } | ||
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| return maxBookmark; | ||
| } | ||
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| private static long bookmarkValue( String value ) | ||
| { | ||
| if ( value.startsWith( BOOKMARK_PREFIX ) ) | ||
| { | ||
| try | ||
| { | ||
| return Long.parseLong( value.substring( BOOKMARK_PREFIX.length() ) ); | ||
| } | ||
| catch ( NumberFormatException e ) | ||
| { | ||
| return UNKNOWN_BOOKMARK_VALUE; | ||
| } | ||
| } | ||
| return UNKNOWN_BOOKMARK_VALUE; | ||
| } | ||
| } | ||
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This method name is confusing in a way that I would question why only return one bookmark rather than all of them back (like toString method).
Maybe change to names like
asSingleString(), ormaxBookmarkAsString, orsingleBookmarkAsString?