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Refactoring BTreeReader and binary search code

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This commit is contained in:
vlofgren 2022-06-20 12:35:58 +02:00
parent 8139ab0d1d
commit 1068694db6
1 changed files with 20 additions and 14 deletions
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28
marginalia_nu/src/main/java/nu/marginalia/util/btree/BTreeReader.java
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@ -5,6 +5,8 @@ import nu.marginalia.util.btree.model.BTreeHeader;
import nu.marginalia.util.multimap.MultimapFileLong; import nu.marginalia.util.multimap.MultimapFileLong;
import nu.marginalia.util.multimap.MultimapSearcher; import nu.marginalia.util.multimap.MultimapSearcher;
import javax.annotation.CheckReturnValue;
import static java.lang.Math.min; import static java.lang.Math.min;
public class BTreeReader { public class BTreeReader {
@ -37,19 +39,22 @@ public class BTreeReader {
final long key = keyRaw & ctx.equalityMask(); final long key = keyRaw & ctx.equalityMask();
final long dataAddress = header.dataOffsetLongs(); final long dataAddress = header.dataOffsetLongs();
if (header.layers() == 0) { // For small data, we only have a data block final long searchStart;
return dataSearcher.binarySearch(key, dataAddress, header.numEntries()); final long numEntries;
}
// Search index layers if (header.layers() == 0) { // For small data, there is no index block, only a flat data block
searchStart = dataAddress;
numEntries = header.numEntries();
}
else {
long dataLayerOffset = searchIndex(header, key); long dataLayerOffset = searchIndex(header, key);
if (dataLayerOffset < 0) { if (dataLayerOffset < 0) {
return dataLayerOffset; return dataLayerOffset;
} }
// Search the corresponding data block searchStart = dataAddress + dataLayerOffset * ctx.entrySize();
final long searchStart = dataAddress + dataLayerOffset * ctx.entrySize(); numEntries = min(header.numEntries() - dataLayerOffset, blockSize);
final long numEntries = min(header.numEntries() - dataLayerOffset, blockSize); }
return dataSearcher.binarySearch(key, searchStart, numEntries); return dataSearcher.binarySearch(key, searchStart, numEntries);
} }
@ -61,14 +66,15 @@ public class BTreeReader {
long layerOffset = 0; long layerOffset = 0;
for (int i = header.layers() - 1; i >= 0; --i) { for (int i = header.layers() - 1; i >= 0; --i) {
final long layerBlockOffset = header.relativeIndexLayerOffset(ctx, i) + layerOffset; final long indexLayerBlockOffset = header.relativeIndexLayerOffset(ctx, i) + layerOffset;
final long nextLayerOffset = indexSearch(key, indexAddress + layerBlockOffset, blockSize); final long nextLayerOffset = indexSearch(key, indexAddress + indexLayerBlockOffset, blockSize);
if (nextLayerOffset < 0) if (nextLayerOffset < 0)
return -1; return nextLayerOffset;
layerOffset = blockSize *(nextLayerOffset + layerOffset); layerOffset = blockSize * (nextLayerOffset + layerOffset);
} }
return layerOffset; return layerOffset;
} }