hbase源码分析之get操作之get转化为scan
1，还是先看构造函数
public get(byte [] row) {
this(row, null);
}
public get(byte [] row, rowlock rowlock) {
this.row = row;
if(rowlock != null) {
this.lockid = rowlock.getlockid();
}
}
public get addfamily(byte [] family) {
familymap.remove(family);
familymap.put(family, null);
return this;
}
public get addcolumn(byte [] family, byte [] qualifier) {
navigableset set = familymap.get(family);
if(set == null) {
set = new treeset(bytes.bytes_comparator);
}
set.add(qualifier);
familymap.put(family, set);
return this;
public get addcolumn(final byte [] column) {
if (column == null) return this;
byte [][] split = keyvalue.parsecolumn(column);
if (split.length > 1 && split[1] != null && split[1].length > 0) {
addcolumn(split[0], split[1]);
} else {
addfamily(split[0]);
}
return this;
}
2，htable.java 里的get方法，，实则是调用了hregionserver的get方法。
public result get(final get get) throws ioexception {
return connection.getregionserverwithretries(
new servercallable(connection, tablename, get.getrow()) {
public result call() throws ioexception {
return server.get(location.getregioninfo().getregionname(), get);
}
}
);
}
3,再来看看hregionserver.java
/** {@inheritdoc} */
public result get(byte[] regionname, get get) throws ioexception {
checkopen();
requestcount.incrementandget();
try {
hregion region = getregion(regionname);
return region.get(get, getlockfromid(get.getlockid()));
} catch (throwable t) {
throw convertthrowabletoioe(cleanup(t));
}
}
再来看看hregion的get方法：
1），首先是检测family,保证table中的family与get中的一致
public result get(final get get, final integer lockid) throws ioexception {
// verify families are all valid
if (get.hasfamilies()) {
for (byte [] family: get.familyset()) {
checkfamily(family);
}
} else { // adding all families to scanner
for (byte[] family: regioninfo.gettabledesc().getfamilieskeys()) {
get.addfamily(family);
}
}
list result = get(get);
return new result(result);
}
最终get其实是转化为scan了
/*
* do a get based on the get parameter.
*/
private list get(final get get) throws ioexception {
scan scan = new scan(get);
list results = new arraylist();
internalscanner scanner = null;
try {
scanner = getscanner(scan);
scanner.next(results);
} finally {
if (scanner != null)
scanner.close();
}
return results;
}