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| 1 | +/* |
| 2 | + * Licensed to the Apache Software Foundation (ASF) under one |
| 3 | + * or more contributor license agreements. See the NOTICE file |
| 4 | + * distributed with this work for additional information |
| 5 | + * regarding copyright ownership. The ASF licenses this file |
| 6 | + * to you under the Apache License, Version 2.0 (the |
| 7 | + * "License"); you may not use this file except in compliance |
| 8 | + * with the License. You may obtain a copy of the License at |
| 9 | + * |
| 10 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | + * |
| 12 | + * Unless required by applicable law or agreed to in writing, |
| 13 | + * software distributed under the License is distributed on an |
| 14 | + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 15 | + * KIND, either express or implied. See the License for the |
| 16 | + * specific language governing permissions and limitations |
| 17 | + * under the License. |
| 18 | + */ |
| 19 | +package org.apache.bookkeeper.mledger.impl; |
| 20 | + |
| 21 | +import static org.apache.bookkeeper.mledger.impl.cache.RangeEntryCacheImpl.BOOKKEEPER_READ_OVERHEAD_PER_ENTRY; |
| 22 | +import static org.apache.bookkeeper.mledger.impl.cache.RangeEntryCacheImpl.DEFAULT_ESTIMATED_ENTRY_SIZE; |
| 23 | +import java.util.Collection; |
| 24 | +import java.util.Map; |
| 25 | +import java.util.NavigableMap; |
| 26 | +import org.apache.bookkeeper.client.LedgerHandle; |
| 27 | +import org.apache.bookkeeper.mledger.Position; |
| 28 | +import org.apache.bookkeeper.mledger.PositionFactory; |
| 29 | +import org.apache.bookkeeper.mledger.proto.MLDataFormats; |
| 30 | + |
| 31 | +class EntryCountEstimator { |
| 32 | + // Prevent instantiation, this is a utility class with only static methods |
| 33 | + private EntryCountEstimator() { |
| 34 | + } |
| 35 | + |
| 36 | + /** |
| 37 | + * Estimates the number of entries that can be read within the specified byte size starting from the given position |
| 38 | + * in the ledger. |
| 39 | + * |
| 40 | + * @param maxEntries stop further estimation if the number of estimated entries exceeds this value |
| 41 | + * @param maxSizeBytes the maximum size in bytes for the entries to be estimated |
| 42 | + * @param readPosition the position in the ledger from where to start reading |
| 43 | + * @param ml the {@link ManagedLedgerImpl} instance to use for accessing ledger information |
| 44 | + * @return the estimated number of entries that can be read |
| 45 | + */ |
| 46 | + static int estimateEntryCountByBytesSize(int maxEntries, long maxSizeBytes, Position readPosition, |
| 47 | + ManagedLedgerImpl ml) { |
| 48 | + LedgerHandle currentLedger = ml.getCurrentLedger(); |
| 49 | + // currentLedger is null in ReadOnlyManagedLedgerImpl |
| 50 | + Long lastLedgerId = currentLedger != null ? currentLedger.getId() : null; |
| 51 | + long lastLedgerTotalSize = ml.getCurrentLedgerSize(); |
| 52 | + long lastLedgerTotalEntries = ml.getCurrentLedgerEntries(); |
| 53 | + return internalEstimateEntryCountByBytesSize(maxEntries, maxSizeBytes, readPosition, ml.getLedgersInfo(), |
| 54 | + lastLedgerId, lastLedgerTotalEntries, lastLedgerTotalSize); |
| 55 | + } |
| 56 | + |
| 57 | + /** |
| 58 | + * Internal method to estimate the number of entries that can be read within the specified byte size. |
| 59 | + * This method is used for unit testing to validate the logic without directly accessing {@link ManagedLedgerImpl}. |
| 60 | + * |
| 61 | + * @param maxEntries stop further estimation if the number of estimated entries exceeds this value |
| 62 | + * @param maxSizeBytes the maximum size in bytes for the entries to be estimated |
| 63 | + * @param readPosition the position in the ledger from where to start reading |
| 64 | + * @param ledgersInfo a map of ledger ID to {@link MLDataFormats.ManagedLedgerInfo.LedgerInfo} containing |
| 65 | + * metadata for ledgers |
| 66 | + * @param lastLedgerId the ID of the last active ledger in the managed ledger |
| 67 | + * @param lastLedgerTotalEntries the total number of entries in the last active ledger |
| 68 | + * @param lastLedgerTotalSize the total size in bytes of the last active ledger |
| 69 | + * @return the estimated number of entries that can be read |
| 70 | + */ |
| 71 | + static int internalEstimateEntryCountByBytesSize(int maxEntries, long maxSizeBytes, Position readPosition, |
| 72 | + NavigableMap<Long, MLDataFormats.ManagedLedgerInfo.LedgerInfo> |
| 73 | + ledgersInfo, |
| 74 | + Long lastLedgerId, long lastLedgerTotalEntries, |
| 75 | + long lastLedgerTotalSize) { |
| 76 | + if (maxSizeBytes <= 0) { |
| 77 | + // If the specified maximum size is invalid (e.g., non-positive), return 0 |
| 78 | + return 0; |
| 79 | + } |
| 80 | + |
| 81 | + // If the maximum size is Long.MAX_VALUE, return the maximum number of entries |
| 82 | + if (maxSizeBytes == Long.MAX_VALUE) { |
| 83 | + return maxEntries; |
| 84 | + } |
| 85 | + |
| 86 | + // Adjust the read position to ensure it falls within the valid range of available ledgers. |
| 87 | + // This handles special cases such as EARLIEST and LATEST positions by resetting them |
| 88 | + // to the first available ledger or the last active ledger, respectively. |
| 89 | + if (lastLedgerId != null && readPosition.getLedgerId() > lastLedgerId.longValue()) { |
| 90 | + readPosition = PositionFactory.create(lastLedgerId, Math.max(lastLedgerTotalEntries - 1, 0)); |
| 91 | + } else if (lastLedgerId == null && readPosition.getLedgerId() > ledgersInfo.lastKey()) { |
| 92 | + Map.Entry<Long, MLDataFormats.ManagedLedgerInfo.LedgerInfo> lastEntry = ledgersInfo.lastEntry(); |
| 93 | + readPosition = |
| 94 | + PositionFactory.create(lastEntry.getKey(), Math.max(lastEntry.getValue().getEntries() - 1, 0)); |
| 95 | + } else if (readPosition.getLedgerId() < ledgersInfo.firstKey()) { |
| 96 | + readPosition = PositionFactory.create(ledgersInfo.firstKey(), 0); |
| 97 | + } |
| 98 | + |
| 99 | + long estimatedEntryCount = 0; |
| 100 | + long remainingBytesSize = maxSizeBytes; |
| 101 | + // Start with a default estimated average size per entry, including any overhead |
| 102 | + long currentAvgSize = DEFAULT_ESTIMATED_ENTRY_SIZE + BOOKKEEPER_READ_OVERHEAD_PER_ENTRY; |
| 103 | + // Get a collection of ledger info starting from the read position |
| 104 | + Collection<MLDataFormats.ManagedLedgerInfo.LedgerInfo> ledgersAfterReadPosition = |
| 105 | + ledgersInfo.tailMap(readPosition.getLedgerId(), true).values(); |
| 106 | + |
| 107 | + // calculate the estimated entry count based on the remaining bytes and ledger metadata |
| 108 | + for (MLDataFormats.ManagedLedgerInfo.LedgerInfo ledgerInfo : ledgersAfterReadPosition) { |
| 109 | + if (remainingBytesSize <= 0 || estimatedEntryCount >= maxEntries) { |
| 110 | + // Stop processing if there are no more bytes remaining to allocate for entries |
| 111 | + // or if the estimated entry count exceeds the maximum allowed entries |
| 112 | + break; |
| 113 | + } |
| 114 | + long ledgerId = ledgerInfo.getLedgerId(); |
| 115 | + long ledgerTotalSize = ledgerInfo.getSize(); |
| 116 | + long ledgerTotalEntries = ledgerInfo.getEntries(); |
| 117 | + |
| 118 | + // Adjust ledger size and total entry count if this is the last active ledger since the |
| 119 | + // ledger metadata doesn't include the current ledger's size and entry count |
| 120 | + // the lastLedgerId is null in ReadOnlyManagedLedgerImpl |
| 121 | + if (lastLedgerId != null && ledgerId == lastLedgerId.longValue() |
| 122 | + && lastLedgerTotalSize > 0 && lastLedgerTotalEntries > 0) { |
| 123 | + ledgerTotalSize = lastLedgerTotalSize; |
| 124 | + ledgerTotalEntries = lastLedgerTotalEntries; |
| 125 | + } |
| 126 | + |
| 127 | + // Skip processing ledgers that have no entries or size |
| 128 | + if (ledgerTotalEntries == 0 || ledgerTotalSize == 0) { |
| 129 | + continue; |
| 130 | + } |
| 131 | + |
| 132 | + // Update the average entry size based on the current ledger's size and entry count |
| 133 | + currentAvgSize = Math.max(1, ledgerTotalSize / ledgerTotalEntries) |
| 134 | + + BOOKKEEPER_READ_OVERHEAD_PER_ENTRY; |
| 135 | + |
| 136 | + // Calculate the total size of this ledger, inclusive of bookkeeping overhead per entry |
| 137 | + long ledgerTotalSizeWithBkOverhead = |
| 138 | + ledgerTotalSize + ledgerTotalEntries * BOOKKEEPER_READ_OVERHEAD_PER_ENTRY; |
| 139 | + |
| 140 | + // If the remaining bytes are insufficient to read the full ledger, estimate the readable entries |
| 141 | + // or when the read position is beyond the first entry in the ledger |
| 142 | + if (remainingBytesSize < ledgerTotalSizeWithBkOverhead |
| 143 | + || readPosition.getLedgerId() == ledgerId && readPosition.getEntryId() > 0) { |
| 144 | + long entryCount; |
| 145 | + if (readPosition.getLedgerId() == ledgerId && readPosition.getEntryId() > 0) { |
| 146 | + entryCount = Math.max(ledgerTotalEntries - readPosition.getEntryId(), 1); |
| 147 | + } else { |
| 148 | + entryCount = ledgerTotalEntries; |
| 149 | + } |
| 150 | + // Estimate how many entries can fit within the remaining bytes |
| 151 | + long entriesToRead = Math.min(Math.max(1, remainingBytesSize / currentAvgSize), entryCount); |
| 152 | + estimatedEntryCount += entriesToRead; |
| 153 | + remainingBytesSize -= entriesToRead * currentAvgSize; |
| 154 | + } else { |
| 155 | + // If the full ledger can be read, add all its entries to the count and reduce its size |
| 156 | + estimatedEntryCount += ledgerTotalEntries; |
| 157 | + remainingBytesSize -= ledgerTotalSizeWithBkOverhead; |
| 158 | + } |
| 159 | + } |
| 160 | + |
| 161 | + // Add any remaining bytes to the estimated entry count considering the current average entry size |
| 162 | + if (remainingBytesSize > 0 && estimatedEntryCount < maxEntries) { |
| 163 | + estimatedEntryCount += remainingBytesSize / currentAvgSize; |
| 164 | + } |
| 165 | + |
| 166 | + // Ensure at least one entry is always returned as the result |
| 167 | + return Math.max((int) Math.min(estimatedEntryCount, maxEntries), 1); |
| 168 | + } |
| 169 | +} |
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