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Lock-free document store—optimized for high rate atomic state changes—that concurrently commits and compacts on-disk log-structured storage files without blocking parallel in-memory updates to associative B-tree maps, spatial Q-tree maps, sequential S-tree lists, and singleton U-tree values
// Copyright 2015-2020 SWIM.AI inc.
//
// 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 swim.db;
import java.util.NoSuchElementException;
import swim.concurrent.Sync;
import swim.structure.Slot;
import swim.util.Cursor;
abstract class STreeNodeCursor implements Cursor {
final STreeNode page;
long index;
int childIndex;
Cursor childCursor;
STreeNodeCursor(STreeNode page, long index, int childIndex) {
this.page = page;
this.index = index;
this.childIndex = childIndex;
}
STreeNodeCursor(STreeNode page) {
this(page, 0L, 0);
}
abstract Cursor childCursor(STreePageRef childRef);
@Override
public final boolean isEmpty() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasNext()) {
return false;
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex;
if (childIndex < childRefs.length) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex + 1;
} else {
return true;
}
}
} while (true);
}
@Override
public final Slot head() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasNext()) {
return childCursor.head();
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex;
if (childIndex < childRefs.length) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex + 1;
} else {
throw new NoSuchElementException();
}
}
} while (true);
}
@Override
public final void step() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasNext()) {
this.index += 1L;
return;
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex;
if (childIndex < childRefs.length) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex + 1;
} else {
throw new UnsupportedOperationException();
}
}
} while (true);
}
@Override
public final void skip(long count) {
while (count > 0L) {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasNext()) {
this.index += 1L;
count -= 1L;
childCursor.next();
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex;
if (childIndex < childRefs.length) {
final STreePageRef childRef = childRefs[childIndex];
final long childSpan = childRef.span;
this.childIndex = childIndex + 1;
if (childSpan < count) {
this.childCursor = childCursor(childRef);
if (count > 0L) {
this.index += count;
this.childCursor.skip(count);
count = 0L;
}
break;
} else {
this.index += childSpan;
count -= childSpan;
}
} else {
break;
}
}
}
}
@Override
public final boolean hasNext() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasNext()) {
return true;
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex;
if (childIndex < childRefs.length) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex + 1;
} else {
return false;
}
}
} while (true);
}
@Override
public final long nextIndexLong() {
return this.index;
}
@Override
public final Slot next() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasNext()) {
this.index += 1L;
return childCursor.next();
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex;
if (childIndex < childRefs.length) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex + 1;
} else {
throw new NoSuchElementException();
}
}
} while (true);
}
@Override
public final boolean hasPrevious() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasPrevious()) {
return true;
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex - 1;
if (childIndex >= 0) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex;
} else {
return false;
}
}
} while (true);
}
@Override
public final long previousIndexLong() {
return this.index - 1L;
}
@Override
public final Slot previous() {
do {
final Cursor childCursor = this.childCursor;
if (childCursor != null) {
if (childCursor.hasPrevious()) {
this.index -= 1L;
return childCursor.previous();
} else {
this.childCursor = null;
}
} else {
final STreePageRef[] childRefs = this.page.childRefs;
final int childIndex = this.childIndex - 1;
if (childIndex < childRefs.length) {
this.childCursor = childCursor(childRefs[childIndex]);
this.childIndex = childIndex;
} else {
throw new NoSuchElementException();
}
}
} while (true);
}
@Override
public void load() throws InterruptedException {
final Sync syncPage = new Sync();
page.pageRef.loadTreeAsync(false, syncPage);
syncPage.await(page.pageRef.settings().pageLoadTimeout);
}
}