从0开始：500行代码实现 LSM 数据库
复制/**
* 从内存表转化为ssTable
* @param index
*/
private void initFromIndex(TreeMap<String, Command> index) {
try {
JSONObject partData = new JSONObject(true);
tableMetaInfo.setDataStart(tableFile.getFilePointer());
for (Command command : index.values()) {
//处理set命令
if (command instanceof SetCommand) {
SetCommand set = (SetCommand) command;
partData.put(set.getKey(), set);
}
//处理RM命令
if (command instanceof RmCommand) {
RmCommand rm = (RmCommand) command;
partData.put(rm.getKey(), rm);
}
//达到分段数量，开始写入数据段
if (partData.size() >= tableMetaInfo.getPartSize()) {
writeDataPart(partData);
}
}
//遍历完之后如果有剩余的数据（尾部数据不一定达到分段条件）写入文件
if (partData.size() > 0) {
writeDataPart(partData);
}
long dataPartLen = tableFile.getFilePointer() - tableMetaInfo.getDataStart();
tableMetaInfo.setDataLen(dataPartLen);
//保存稀疏索引
byte[] indexBytes = JSONObject.toJSONString(sparseIndex).getBytes(StandardCharsets.UTF_8);
tableMetaInfo.setIndexStart(tableFile.getFilePointer());
tableFile.write(indexBytes);
tableMetaInfo.setIndexLen(indexBytes.length);
LoggerUtil.debug(LOGGER, "[SsTable][initFromIndex][sparseIndex]: {}", sparseIndex);
//保存文件索引
tableMetaInfo.writeToFile(tableFile);
LoggerUtil.info(LOGGER, "[SsTable][initFromIndex]: {},{}", filePath, tableMetaInfo);
} catch (Throwable t) {
throw new RuntimeException(t);
}
}
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