Examples with PageCursor org.neo4j.io.pagecache.PageCursor used on opensource projects

Example 86 with PageCursor

use of org.neo4j.io.pagecache.PageCursor in project neo4j by neo4j.

the class FreeListIdProvider method acquireNewIdFromFreelistOrEnd.

private long acquireNewIdFromFreelistOrEnd(long stableGeneration, long unstableGeneration, boolean allowTakeLastFromPage) throws IOException {
    if ((readPageId != writePageId || readPos < writePos) && (allowTakeLastFromPage || readPos < freelistNode.maxEntries() - 1)) {
        // or the read pos is < write pos so check if we can grab the next id (generation could still mismatch).
        try (PageCursor cursor = pagedFile.io(readPageId, PagedFile.PF_SHARED_READ_LOCK)) {
            if (!cursor.next()) {
                throw new IOException("Couldn't go to free-list read page " + readPageId);
            }
            long resultPageId;
            do {
                resultPageId = freelistNode.read(cursor, stableGeneration, readPos);
            } while (cursor.shouldRetry());
            if (resultPageId != FreelistNode.NO_PAGE_ID) {
                // FreelistNode compares generation and so this means that we have an available
                // id in the free list which we can acquire from a stable generation. Increment readPos
                readPos++;
                if (readPos >= freelistNode.maxEntries()) {
                    // The current reader page is exhausted, go to the next free-list page.
                    readPos = 0;
                    do {
                        readPageId = FreelistNode.next(cursor);
                    } while (cursor.shouldRetry());
                    // Put the exhausted free-list page id itself on the free-list
                    long exhaustedFreelistPageId = cursor.getCurrentPageId();
                    releaseId(stableGeneration, unstableGeneration, exhaustedFreelistPageId);
                    monitor.releasedFreelistPageId(exhaustedFreelistPageId);
                }
                return resultPageId;
            }
        }
    }
    // Fall-back to acquiring at the end of the file
    return nextLastId();
}

Example 87 with PageCursor

use of org.neo4j.io.pagecache.PageCursor in project neo4j by neo4j.

the class FreeListIdProvider method acquireNewId.

private long acquireNewId(long stableGeneration, long unstableGeneration, boolean allowTakeLastFromPage) throws IOException {
    // Acquire id from free-list or end of store file
    long acquiredId = acquireNewIdFromFreelistOrEnd(stableGeneration, unstableGeneration, allowTakeLastFromPage);
    // Zap the page, i.e. set all bytes to zero
    try (PageCursor cursor = pagedFile.io(acquiredId, PagedFile.PF_SHARED_WRITE_LOCK)) {
        PageCursorUtil.goTo(cursor, "newly allocated free-list page", acquiredId);
        cursor.zapPage();
    // don't initialize node here since this acquisition can be used both for tree nodes
    // as well as free-list nodes.
    }
    return acquiredId;
}

Example 88 with PageCursor

use of org.neo4j.io.pagecache.PageCursor in project neo4j by neo4j.

the class GBPTree method writerHeader.

private static void writerHeader(PagedFile pagedFile, Header.Writer headerWriter, TreeState otherState, PageCursor cursor) throws IOException {
    // Write/carry over header
    int headerOffset = cursor.getOffset();
    // will contain length of written header data (below)
    int headerDataOffset = headerOffset + Integer.BYTES;
    if (otherState.isValid()) {
        PageCursor previousCursor = pagedFile.io(otherState.pageId(), PagedFile.PF_SHARED_READ_LOCK);
        PageCursorUtil.goTo(previousCursor, "previous state page", otherState.pageId());
        do {
            // Place the previous state cursor after state data
            TreeState.read(previousCursor);
            // Read length of previous header
            int previousLength = previousCursor.getInt();
            // Reserve space to store length
            cursor.setOffset(headerDataOffset);
            // Write
            headerWriter.write(previousCursor, previousLength, cursor);
        } while (previousCursor.shouldRetry());
        checkOutOfBounds(previousCursor);
        checkOutOfBounds(cursor);
        int length = cursor.getOffset() - headerDataOffset;
        cursor.putInt(headerOffset, length);
    }
}

Example 89 with PageCursor

use of org.neo4j.io.pagecache.PageCursor in project neo4j by neo4j.

the class GBPTree method readMeta.

private void readMeta(File indexFile, Layout<KEY, VALUE> layout, PagedFile pagedFile) throws IOException {
    // Read meta
    int formatVersion;
    long layoutIdentifier;
    int majorVersion;
    int minorVersion;
    try (PageCursor metaCursor = openMetaPageCursor(pagedFile, PagedFile.PF_SHARED_READ_LOCK)) {
        do {
            formatVersion = metaCursor.getInt();
            pageSize = metaCursor.getInt();
            layoutIdentifier = metaCursor.getLong();
            majorVersion = metaCursor.getInt();
            minorVersion = metaCursor.getInt();
            layout.readMetaData(metaCursor);
        } while (metaCursor.shouldRetry());
        checkOutOfBounds(metaCursor);
        metaCursor.checkAndClearCursorException();
    } catch (CursorException e) {
        throw new MetadataMismatchException(format("Tried to open %s, but caught an error while reading meta data. " + "File is expected to be corrupt, try to rebuild.", indexFile), e);
    }
    if (formatVersion != FORMAT_VERSION) {
        throw new MetadataMismatchException("Tried to open %s with a different format version than " + "what it was created with. Created with:%d, opened with %d", indexFile, formatVersion, FORMAT_VERSION);
    }
    if (layoutIdentifier != layout.identifier()) {
        throw new MetadataMismatchException("Tried to open " + indexFile + " using different layout identifier " + "than what it was created with. Created with:" + layoutIdentifier + ", opened with " + layout.identifier());
    }
    if (majorVersion != layout.majorVersion() || minorVersion != layout.minorVersion()) {
        throw new MetadataMismatchException("Tried to open " + indexFile + " using different layout version " + "than what it was created with. Created with:" + majorVersion + "." + minorVersion + ", opened with " + layout.majorVersion() + "." + layout.minorVersion());
    }
}

Example 90 with PageCursor

use of org.neo4j.io.pagecache.PageCursor in project neo4j by neo4j.

the class MuninnPageCacheTest method mustFlushDirtyPagesOnEvictingFirstPage.

@Test
public void mustFlushDirtyPagesOnEvictingFirstPage() throws Exception {
    writeInitialDataTo(file("a"));
    RecordingPageCacheTracer tracer = new RecordingPageCacheTracer();
    RecordingPageCursorTracer cursorTracer = new RecordingPageCursorTracer();
    ConfigurablePageCursorTracerSupplier cursorTracerSupplier = new ConfigurablePageCursorTracerSupplier(cursorTracer);
    MuninnPageCache pageCache = createPageCache(fs, 2, 8, blockCacheFlush(tracer), cursorTracerSupplier);
    PagedFile pagedFile = pageCache.map(file("a"), 8);
    try (PageCursor cursor = pagedFile.io(0, PF_SHARED_WRITE_LOCK)) {
        assertTrue(cursor.next());
        cursor.putLong(0L);
    }
    cursorTracer.reportEvents();
    assertNotNull(cursorTracer.observe(Fault.class));
    assertEquals(1, cursorTracer.faults());
    assertEquals(1, tracer.faults());
    int clockArm = pageCache.evictPages(1, 0, tracer.beginPageEvictions(1));
    assertThat(clockArm, is(1));
    assertNotNull(tracer.observe(Evict.class));
    ByteBuffer buf = ByteBuffer.allocate(16);
    StoreChannel channel = fs.open(file("a"), "r");
    channel.read(buf);
    buf.flip();
    assertThat(buf.getLong(), is(0L));
    assertThat(buf.getLong(), is(y));
}