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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | 1x 1x 1x 1x 1x 1x 4x 4x 4x 4x 4x | import { Logger } from "../../../logger";
import { IRequest } from "../../../server/request";
import { DataType } from "../../data/data-type";
import { Database } from "../../data/database";
import { DatabaseValue } from "../../data/database-value";
import { RedisToken } from "../../protocol/redis-token";
import { IRespCommand } from "../resp-command";
/**
* ### Available since 1.0.0.
* ### GETSET key value
* Atomically sets key to value and returns the old value stored at key. Returns an error when
* key exists but does not hold a string value.
*
* ### Design pattern
* GETSET can be used together with {@link resp/command/string/incr-command.IncrCommand | INCR} for counting with atomic reset.
* For example: a process
* may call INCR against the key mycounter every time some event occurs, but from time to time we
* need to get the value of the counter and reset it to zero atomically. This can be done using
* GETSET mycounter "0":
* ### Example
* ```
* redis> INCR mycounter
* (integer) 1
* redis> GETSET mycounter "0"
* "1"
* redis> GET mycounter
* "0"
* redis>
* ```
* ### Return value
* Bulk string reply: the old value stored at key, or nil when key did not exist.
*/
export class GetSetCommand extends IRespCommand {
public DbDataType = DataType.STRING
public maxParams = 2
public minParams = 2
public name = "getset"
private logger: Logger = new Logger(module.id);
public execSync(request: IRequest, db: Database): RedisToken {
this.logger.debug(
`${request.getCommand()}.execute(%s)`,
...request.getParams()
);
const key: string = request.getParam(0);
let result: RedisToken;
const dbValue: DatabaseValue = db.get(key);
if (!dbValue) {
result = RedisToken.nullString();
} else {
result = RedisToken.string(dbValue.getString());
}
const newValue: string = request.getParam(1);
db.put(
key,
new DatabaseValue(
DataType.STRING,
newValue
)
);
return result;
}
}
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