我正在努力改变现有的排队系统......这让我很头疼......
队列背后的逻辑全部在Oracle DB中，如下所示：
对调度JOB没有太多控制权，因此我决定寻找更好地调度工作的整个框架的方法。我必须添加它是一个旧的实现，可以工作很长一段时间，但大多数都不容易控制或透明。
我的观点是，这个调度过程有没有安全的方法？
提前致谢。
答案 0 :(得分：1)
考虑到不断运行的工作，可以通过DBMS_PIPE发送消息来控制程序执行。
控制代码通过dbms_pipe发送stop消息
Dispatcher代码在DBMS_SCHEDULER作业中不断运行，并检查stop消息是否到达管道
也可以在一些超时后强制中断DBMS_SHCEDULER作业。
多年前，我已经实现了这样的逻辑，这个解决方案一直运行到现在。下面的代码是一个改编的样本，可以帮助您检查这种方法是否可以接受并适用于您的案例。
控制包标题：
create or replace package DispatcherControl is
-- Package to control job state
procedure StartDispatcher;
procedure StopDispatcher;
end;
控制包体：
create or replace package body DispatcherControl is
-- User who owns dispatcher job in DBMS_SCHEDULER
C_DISPATCH_PROGRAM_OWNER constant varchar2(100) := 'DISPATCH_USER';
-- Main procedure to handle dispatcher requests
C_DISPATCH_JOB_PROC constant varchar2(100) := 'DISPATCH_USER.DISPATCHER.MAINPROC';
-- Name for dispatch program
C_DISPATCH_PROGRAM_NAME constant varchar2(100) := 'DISPATCH_PROGRAM';
-- Description for dispatch program
C_DISPATCH_PROGRAM_COMMENT constant varchar2(100) := 'Q1 dispatch task';
-- Dispatcher job name.
C_DISPATCH_JOB_NAME constant varchar2(100) := 'DISPATCH_JOB';
-- Description for dispatcher job
C_DISPATCH_JOB_COMMENT constant varchar2(100) := 'Q1 dispatch process';
-- Pipe name for dispatch job control.
C_DISPATCH_PIPE_NAME constant varchar2(100) := 'DISPATCH_CONTROL';
-- Message text for pipe to stop dispatch job
C_PIPE_STOP_MSG constant varchar2(100) := 'stop_dispatch';
-- Check if DBMS_SCHEDULER program exists and create it if needed
procedure CheckDispatcherJobExists
is
begin
-- Return if program exists
for cDummy in (
select 1
from all_scheduler_programs
where
owner = C_DISPATCH_PROGRAM_OWNER and program_name = C_DISPATCH_PROGRAM_NAME
and
rownum = 1
) loop
return;
end loop;
-- Create disabled if not found
sys.dbms_scheduler.create_program(
program_name => C_DISPATCH_PROGRAM_OWNER || '.' || C_DISPATCH_PROGRAM_NAME,
program_type => 'STORED_PROCEDURE',
program_action => C_DISPATCH_JOB_PROC,
number_of_arguments => 0,
enabled => false,
comments => C_DISPATCH_PROGRAM_COMMENT
);
-- Enable program
sys.dbms_scheduler.enable(C_DISPATCH_PROGRAM_OWNER || '.' || C_DISPATCH_PROGRAM_NAME);
end;
-- Check status of dispatcher job and run it if not found
procedure CheckDispatcherJobState
is
begin
CheckDIspatcherJobExists;
-- Check if job is currently running according to scheduler info
for cDummy in (
select * from all_scheduler_jobs
where
owner = C_DISPATCH_PROGRAM_OWNER
and
job_name = C_DISPATCH_JOB_NAME
) loop
-- Job found, check if running
for cDummy2 in (
select * from all_scheduler_running_jobs
where
owner = C_CIS_PROGRAM_OWNER and job_name = C_DISPATCH_JOB_NAME
) loop
-- Check if job really running by checking sessions list
for cDummy3 in (
select 1
from
all_scheduler_running_jobs jobs,
sys.v_$session sessions
where
jobs.owner = C_DISPATCH_PROGRAM_OWNER and jobs.job_name = C_DISPATCH_JOB_NAME
and
sessions.sid = jobs.session_id and sessions.process = jobs.slave_os_process_id
and
sessions.action = jobs.job_name and sessions.username = jobs.owner
and
sessions.module = 'DBMS_SCHEDULER'
) loop
-- Ok, return
return;
end loop;
-- No process found for running job, stop and delete task before recreation
sys.dbms_scheduler.stop_job(C_DISPATCH_JOB_NAME, true);
end loop;
-- process found, but restart needed
sys.dbms_scheduler.drop_job(C_DISPATCH_JOB_NAME, true);
end loop;
-- Create one-time running job with manual start
sys.dbms_scheduler.create_job(
job_name => C_DISPATCH_JOB_NAME,
program_name => C_DISPATCH_PROGRAM_OWNER || '.' || C_DISPATCH_PROGRAM_NAME,
enabled => true,
auto_drop => true,
start_date => add_months(sysdate,1000),
repeat_interval => null,
end_date => null,
comments => C_DISPATCH_JOB_COMMENT
);
-- Run created task
sys.dbms_scheduler.run_job(
job_name => C_DISPATCH_JOB_NAME,
use_current_session => false
);
end;
-- Stop and drop dispatch job.
procedure DropDispatchJob
is
vSendRC integer;
begin
-- Send request through DBMS_PIPE and wait for timeout.
sys.dbms_pipe.reset_buffer;
sys.dbms_pipe.pack_message(C_PIPE_STOP_MSG);
vSendRC := sys.dbms_pipe.send_message(C_DISPATCH_PIPE_NAME,1);
if(vSendRC = 0) then
-- wait if sent Ok
sys.dbms_lock.sleep(0.25);
end if;
-- force job stop (not done in case of drop_job)
for cDummy in (
select 1 from all_scheduler_running_jobs
where
owner = C_DISPATCH_PROGRAM_OWNER
and
job_name = C_DISPATCH_JOB_NAME
) loop
begin
sys.dbms_scheduler.stop_job(C_DISPATCH_JOB_NAME, true);
exception
when others then begin
-- If sqlcode = -27366 then task finished, in other case it's unexpected
if(SQLCODE != -27366) then
raise;
end if;
end;
end;
end loop;
-- delete job if exists, allow stopping
for cDummy in (
select 1 from all_scheduler_jobs
where
owner = C_DISPATCH_PROGRAM_OWNER
and
job_name = C_DISPATCH_JOB_NAME
) loop
sys.dbms_scheduler.drop_job(C_DISPATCH_JOB_NAME, true);
end loop;
-- drop program if exists
for cDummy in (
select 1 from all_scheduler_programs
where
owner = C_DISPATCH_PROGRAM_OWNER
and
program_name = C_DISPATCH_PROGRAM_NAME
) loop
sys.dbms_scheduler.drop_program(C_DISPATCH_PROGRAM_NAME, true);
end loop;
-- Clear DBMS_PIPE messages after job stop (cover case of forced stop).
sys.dbms_pipe.purge(C_DISPATCH_PIPE_NAME);
end;
-- Start dispatcher process
procedure StartDispatcher
is
begin
-- Clear message queue before starting
sys.dbms_pipe.purge(C_DISPATCH_PIPE_NAME);
CheckDispatchJobState;
end;
-- Stop dispatcher process
procedure StopDispatcher
is
begin
DropDispatchJob;
end;
end;
Dispatcher包标题：
create or replace package DISPATCH_USER.Dispatcher is
-- Main queue check procedure to run from job.
procedure MainProc;
end;
Dispatcher包体：
create or replace package body DISPATCH_USER.Dispatcher is
-- Normal wait time in seconds
NORMAL_CHECK_INTERVAL constant number := 0.01;
-- Checks if stop message received.
function CheckIsStopped return boolean
is
vPipeRC integer;
vMsg varchar2(1024);
begin
-- check if message exists
vPipeRC := sys.dbms_pipe.receive_message('DISPATCH_CONTROL',0);
if(vPipeRC = 0) then
-- check type of message content, must be varchar2 (look for constants in sys.dbms_pipe package).
if(sys.dbms_pipe.next_item_type = 9) then
-- check message content
sys.dbms_pipe.unpack_message(vMsg);
if(vMsg = 'stop') then
return true;
end if;
end if;
end if;
return false;
end;
-- Checks if error caused by external interrupt
function IsInterruptError(piSQLCode in number) return boolean
is
begin
if( piSQLCode in (
-1013, -- ORA-01013: User requested cancel of current operation
-28, -- ORA-00028: Your session has been killed
-13638, -- ORA-13638: The user interrupted the current operation
-13639, -- ORA-13639: The current operation was interrupted because it timed out.
-13668, -- ORA-13668: The current operation was aborted because it was blocking another session
-48223, -- ORA-48223: Interrupt Requested - Fetch Aborted - Return Code [string] [string]
-48495 -- ORA-48495: Interrupt requested
)
) then
return true;
end if;
return false;
end;
-- Main procedure for dispatcher job
procedure MainProc
is
vIsFound boolean;
vSQLCode number;
vErrMsg varchar2(2048);
vCheckInterval number;
vMESSAGE SOME_CUSTOM_MESSAGE_DATA_TYPE; -- Just for example
begin
vCheckInterval := NORMAL_CHECK_INTERVAL;
while(true) loop
vIsFound := false;
begin
vMESSAGE := GET_NEXT_MESSAGE_FROM_QUEUE; -- Just for example
if(vMESSAGE is not null) then
vIsFound := true;
-- Process received message her
DISPATCH_MESSAGE(vMESSAGE); -- Just for example
-- Commit changes to save a redo log from overflow.
commit;
end if;
exception
when others then begin
vSQLCode := SQLCODE;
vErrMsg := SQLERRM;
if( IsInterruptError(vSQLCode) ) then
-- Promote error if interrupted forcibly
raise;
end if;
-- In other cases just write error conditions to log and continue.
-- Log writing totally skipped from this example, so only comment here.
-- Also it's a place to perform extra error analysis.
-- E.g. if it is some temporary error caused by remote database shutdown
-- and so on, then increase vCheckInterval and don't stress server.
end;
end;
-- Check if interrupted programmatically from control procedure
if( CheckIsStopped ) then
-- normal exit, job finished
return;
end if;
-- If there are no new request then put process in sleep state
-- for a short time to release resources
if(not vIsFound) then
dbms_lock.sleep(vCheckInterval);
end if;
end loop;
-- This point never reached
null;
end;
end;
请注意，上面的代码是一个简化的示例（例如，没有记录执行的活动）。此外，采用示例代码来匹配问题条件，并包含一些假设，如Oracle用户名和GET_NEXT_MESSAGE_FROM_QUEUE等泛型。请随意询问示例代码中是否有不明确的内容。