redis实现异步任务队列
先说思路：
将任务对象序列为JSON字符串，然后推入REDIS缓存，这叫入队。
通过独立的工作线程从REDIS拉出一个任务，这叫出队，工作线程将JSON字符串还原为任务对象，然后对这个任务对象进行处理，并取得执行结果。
整个过程是全异步执行的，所以叫异步任务队列。
下面附上演示代码。
1）任务对象定义
type
TJob = class
private
FReplyTo: String;
procedure SetReplyTo(const Value: String);
public
property ReplyTo: String read FReplyTo write SetReplyTo;
end; TEvalJob = class(TJob)
private
FExpression: String;
procedure SetExpression(const Value: String);
public
property Expression: String read FExpression write SetExpression;
end; TDatabaseJob = class(TJob)
private
FProcedureName: String;
procedure SetProcedureName(const Value: String);
public
property ProcedureName: String read FProcedureName
write SetProcedureName;
end;
2）入队
procedure TMainForm.Button1Click(Sender: TObject);
var
lRedis: IRedisClient;
lJob: TEvalJob;
lJobString: string;
begin
lRedis := NewRedisClient(REDIS_HOSTNAME); lJob := TEvalJob.Create;
try
lJob.ReplyTo := 'replies:' + FUserName;
lJob.Expression := Edit1.Text;
lJobString := TJson.ObjectToJsonString(lJob);
lRedis.LPUSH('jobs', lJobString);
finally
lJob.free;
end;
end;
3）出队并执行
procedure TMainForm.Timer1Timer(Sender: TObject);
var
lJobj: TJSONObject;
lExpression, lRes: string;
lResponse: string;
begin
if FRedis.RPOP('replies:' + FUserName, lResponse) then
begin
lJobj := TJSONObject.ParseJSONValue(lResponse) as TJSONObject;
try
lExpression := lJobj.GetValue<TJSONString>('expression').Value;
lRes := lJobj.GetValue<TJSONString>('result').Value;
Memo1.Lines.Add(Format('Response: %s = %s', [lExpression, lRes]));
finally
lJobj.free;
end;
end;
end;