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originally posted 2014-03-24 |
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IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[System]') AND type in (N'U')) DROP TABLE [dbo].[System] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[fIsLocked]') AND type in (N'FN', N'IF', N'TF', N'FS', N'FT')) DROP FUNCTION [dbo].[fIsLocked] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[fGetLockProgress]') AND type in (N'FN', N'IF', N'TF', N'FS', N'FT')) DROP FUNCTION [dbo].[fGetLockProgress] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[fGenerateLockName]') AND type in (N'FN', N'IF', N'TF', N'FS', N'FT')) DROP FUNCTION [dbo].[fGenerateLockName] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spTest]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spTest] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spSetProgress]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spSetProgress] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spSetLock]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spSetLock] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spLongRunningQuery]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spLongRunningQuery] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spIsLockedWait]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spIsLockedWait] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spClearLock2]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spClearLock2] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spClearLock]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spClearLock] GO IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[spCancel]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[spCancel] GO CREATE TABLE [dbo].[System]( [Id] [uniqueidentifier] NOT NULL default newsequentialid(), [Lock] [nvarchar](100) NULL, [LockDateTime] [datetime] NULL, [Progress] [int] NULL, [Cancel] [bit] NOT NULL default 0, [LockWaitTimeoutSeconds] [int] NOT NULL default 10, [LockExpireMinutes] [int] NOT NULL default 5, CONSTRAINT [PK_System] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO TRUNCATE TABLE [dbo].[System] GO INSERT [dbo].[System] ([Progress]) values (null) GO create procedure [dbo].[spCancel] as begin if([dbo].[fIsLocked]() = 1) update [dbo].[System] set [Cancel] = 1 end GO create procedure [dbo].[spClearLock](@lockname nvarchar(100) = null) as begin update [dbo].[System] set [Lock] = null where [Lock] like @lockname end GO create procedure [dbo].[spClearLock2] as begin update [dbo].[System] set [Lock] = null end GO create procedure [dbo].[spIsLockedWait] (@waitForSeconds int) as begin --if @waitForSeconds > 0 then wait for @waitForSeconds for the lock to clear --if @waitForSeconds = 0 then don't wait for the lock to clear --if @waitForSeconds is null then use system setting --if @waitForSeconds < 0 then wait until the is cleared. --returns 1 if locked, else 0 if (@waitForSeconds is null) select top 1 @waitForSeconds = [LockWaitTimeoutSeconds] from [dbo].[System] with (nolock) declare @dt datetime = getdate() declare @timedout bit = 0 while([dbo].[fIsLocked]()=1) begin if(@waitForSeconds=0 or (@waitForSeconds > 0 and datediff(s,@dt,getdate())>@waitForSeconds)) begin set @timedout = 1 break; end waitfor delay '0:00:01'; end if(@timedout=1) return [dbo].[fIsLocked](); return 0; end GO create procedure [dbo].[spSetLock](@lockname nvarchar(100), @waitSeconds int) as begin --if @waitForSeconds > 0 then wait for @waitForSeconds for the lock to clear --if @waitForSeconds = 0 or null then don't wait for the lock to clear --if @waitForSeconds is null then use System.[LockTimeoutMinutes] value --if @waitForSeconds < 0 then wait until the is cleared. if ([dbo].[fIsLocked]()=0) begin --set lock update [dbo].[System] set [Lock] = @lockname, [LockDateTime] = getdate(); return 0; end else begin --lock already set declare @lockExpireMinutes int declare @LockDateTime datetime select top 1 @lockExpireMinutes = [LockExpireMinutes] ,@LockDateTime = [LockDateTime] from [dbo].[System] with (nolock) if((select datediff(n, @LockDateTime, getdate())) < @lockExpireMinutes) begin --not within the automatic clear time of @lockExpireMinutes --wait for lock for @waitSeconds declare @islocked bit = null; exec @islocked = [dbo].[spIsLockedWait] @waitSeconds if(@islocked = 0) begin --the existing lock cleared in time, set a new lock update [dbo].[System] set [Lock] = @lockname, [LockDateTime] = getdate(); end else begin declare @msg nvarchar(max) = 'The system is currently running a locking process ''' + (select top 1 [Lock] from [dbo].[System]) + ''' that has locked the requested resources. You may try again once the running process completes.' raiserror(@msg,11,100); return -1; end end else begin --automatically clear the existing lock after @lockTimeoutMinutes and set a new lock update [dbo].[System] set [Lock] = @lockname, [LockDateTime] = getdate(); return 0; end end end GO create procedure [dbo].[spSetProgress](@percent int) as begin declare @isLocked bit = [dbo].[fIsLocked](); if(@percent <= 0) set @percent = 1; if(@percent is null or @percent > 100 or @isLocked = 0) set @percent = 100; update [dbo].[System] set [Progress] = @percent if(@isLocked = 1) begin declare @cancel bit = 0 select top 1 @cancel = [Cancel] from [dbo].[System] with (nolock) if(@cancel = 1) begin update [dbo].[System] set [Cancel] = 0 --clear cancel flag raiserror(' cancel requested.',11,100); return -1; end end end GO create function [dbo].[fGenerateLockName](@seedname nvarchar(50) = null) returns nvarchar(100) as begin declare @name nvarchar(100) = convert(nvarchar(25),datediff(s,'1970-1-1',sysutcdatetime())); if(@seedname is not null) set @name = @seedname + '_' + @name; return @name; end GO create function [dbo].[fGetLockProgress]() returns nvarchar(100) as begin declare @progress int = 100; if([dbo].[fIsLocked]()=1) begin select @progress = [Progress] from [dbo].[System] with (nolock) end return @progress; end GO create function [dbo].[fIsLocked]() returns bit as begin if exists(select top 1 [Lock] from [dbo].[System] with (nolock) where [Lock] is not null and len(ltrim(rtrim([Lock])))>0) return 1; return 0; end GO create procedure [dbo].[spLongRunningQuery] as begin declare @errored bit = 0; declare @msg nvarchar(4000) declare @intrans bit = 0; declare @lock_result int = null; declare @lock nvarchar(100) = [dbo].[fGenerateLockName]('spLongRunningQuery'); declare @count int = 0; begin try --acquire lock exec @lock_result = [dbo].[spSetLock] @lock, null exec [dbo].[spSetProgress] 10 begin transaction set @intrans = 1 while(@count<100) begin exec [dbo].[spSetProgress] @count set @msg = convert(nvarchar(10),@count) raiserror (@msg, 0, 1) with nowait --print immediately waitfor delay '0:00:01'; --pause for a second set @count = @count + 10 end commit transaction end try begin catch --handle error set @errored = 1; set @msg = 'Error : ' + isnull(error_message(),''); if (@intrans = 1) begin rollback transaction end end catch --finalize if(@lock_result = 0) begin --last progress update, ignore any error thrown begin try exec [dbo].[spSetProgress] 100 end try begin catch dummy: end catch --release lock exec [dbo].[spClearLock] @lock end if(@errored=1) begin raiserror(@msg,11,100); return -1 end return 0; end GO create procedure [dbo].[spTest] as begin --TEST QUERY --STEP 1 : exec [spLongRunningQuery] --STEP 2 : Run this test query --NOTE: execute [spCancel] to cancel and rollback changes of [spLongRunningQuery] declare @msg nvarchar(300) declare @percent int = '' declare @lpercent int = '' while(1=1) begin if([dbo].[fIsLocked]()=1) begin set @percent = [dbo].[fGetLockProgress]() set @msg = 'Progress : ' + convert(nvarchar(100),@percent) + ' percent' if(@lpercent<>@percent) raiserror (@msg, 0, 1) with nowait --print immediately set @lpercent = @percent end else break; waitfor delay '0:00:00'; end raiserror ('done.', 0, 1) with nowait --print immediately end GO |