In powershell , for a complicated reason an application needs a 6 character string as a sort of handle (Eg: abcdef) for a long asynchronous operation. I perform this using
$replaceHandle = "abcdef"
start-Job -handle $replaceHandle
The application stores the status of the asynchronous job in $abcdef (Prefixes string with $)
and i can access parameters of job Status at any time by requesting
Get-Status -ID $abcdef.ID
Problem for me in my code is i am not able to get this $abcdef.ID properly
I have tried
$($jobVar.ToString()).ID - this gives blank/errors out
maipulating $$jobVar.ID actually gives $'abcdef'.ID
How do i manage to get value of ($abcdef.ID) appropriately ?
It because $jobVar is first interpreted :
try :
write-host "the value is $($jobVar.ID)"
(Get-Variable $b -ValueOnly).Id
This worked
Related
One thing I noticed when playing around with Lua scripts is that, in a script containing multiple operations, if an error is thrown halfway through the execution of the script, the operations that completed before the error will actually be reflected in the database. This is in contrast to MULTI / EXEC, where either all operations succeed or fail.
For example, if I have a script like the following:
redis.call("hset", "mykey", "myfield", "val")
local expiry = someFunctionThatMightThrow()
redis.call("expire", "mykey", expiry)
I tested this and the results of the first hset call were reflected in redis. Is there any way to make the lua script behave so that if any error is thrown during the script, then all actions performed during that script execution are reverted?
Sample script for my comment above, on error manually rollback. Note: Syntax is not verified.
redis.call("hset", "mykey", "myfield", "val")
local expiry,error = pcall(someFunctionThatMightThrow())
if expiry ~= nil then
redis.call("expire", "mykey", expiry)
else
redis.call("hdel", "mykey", "myfield")
end
I am working in a TCL automation environent at my workplace.
I'm trying to run a delayed command in my script using "after".
The problem i encounter is that when i try to specify commands with variables inside a code block under an "after" , the vars are not recognized and i get an error message.
I'll quote the relevant parts of the code.
proc test_script1 {{bh0 0} ...more vars....} {
.
.
.
after [expr 20000] {
set some_value[ ns1::probe_TCP_connections $bh0 $main_duration 1 15] }
puts "the value i got is $some_value"
}
And i seem to get an error:
can't read "some_value": no such variable
Can anyone suggets what is the problem , and how to oversome it?
thx
You can capture the values of local variables with the help of apply (and it's advisable to use list to build callbacks when they get even slightly non-trivial). Since the body of an apply is a lambda expression with its own scope — a little nameless procedure — you have to use global in it to access state that will persist, and in any case after callbacks are called from the global namespace always (since the mechanism doesn't know how to keep arbitrary stack frames around for the duration of the asynchronous operation).
after 20000 [list apply {{bh0 main_duration} {
global some_value
set some_value [ns1::probe_TCP_connections $bh0 $main_duration 1 15]
}} $bh0 $main_duration]
global some_value
vwait some_value
puts "The value was changed to $some_value"
It's possible to get even more sophisticated, especially in Tcl 8.6 which has a coroutine system that can be used to hide the complexity of using continuation passing style programming.
Here is a proc that will do something similar to what you're trying to do:
proc foo {} {
# Make 'a' available to both the global scope and local scope
global a
# This is to check the current level
puts "Current level: [info level]"
# The command to be run in 500 ms, and I have added another check for the level
after 500 {puts "Current level: [info level]"; set a 100}
# Wait for further execution until the global variable 'a' changes
vwait a
# Prints a
puts "Value of \$a: $a"
}
The output of the above will be:
Current level: 1
# After 500 ms, the below will print
Current level: 0
Value of $a: 100
When you use after, the variable a is being created in the global scope, that is not accessible to the proc unless explicitly given access. One of the simplest ways is to first make sure that a within the proc is accessible both globally and locally, with global (level 0).
I am aware that you can preform simple message passing with the following:
self() ! hello.
and you can see the message by calling:
flush().
I can also create simple processes in functions with something like:
spawn(module, function, args).
However I am not clear how one can send messages to the processes with out registering the Pid.
I have seen examples showing that you can pattern match against this in the shell to get the Pid assigned to a var, so if i create a gen_server such as:
...
start_link() ->
gen_server:start_link(?MODULE, init, []).
init(Pid) ->
{ok, Pid}.
...
I can then call it with the following from the shell:
{ok, Pid} = test_sup:start_link().
{ok,<0.143.0>}
> Pid ! test.
test
So my question is, can you send messages to Pids in the form <0.0.0> with out registering them to an atom or variable in the shell? Experimenting and searching as proved fruitless...
If you happen to need to send a message to a Pid based on the textual representation of its Pid, you can do (assuming the string is "<0.42.0>"):
list_to_pid("<0.42.0>") ! Message
This is almost only useful in the shell (where you can see the output of log messages or monitor data from something like Observer); any spawned process should normally be a child of some form of parent process to which it is linked (or monitored).
As for sending a message to something you just spawned, spawn returns a Pid, so you can assign it directly to a variable (which is not the same as registering it):
Pid = spawn(M, F, A),
Pid ! Message.
If you have the string "" to identify a pid, it is
either because you are working in the shell, and you use the representation you see, and you forgot to store this pid in a variable. Then simply use pid(X,Y,Z) to get it;
either because you did something like io_lib:format("~p",[Val]) where Val is the pid or a an erlang term which contain this pid. Then simply assign the pid to a variable (directly or extracting it from the term). It can be stored in an ets, send to another process without transformation
You should avoid to use the shell (or string) representation. One reason is that this representation is different when you ask the pid of one process from 2 different nodes as shown in the next screen capture.
I am running a very simple query and trying to extract the results to a text file. The entire query is essentially what is below, I am selecting everything from one single table with one piece of where criteria which is limiting the data to one month's worth. After it has extracted around 1.2 gig this error shows up. Is there any way that I can work around this other than extracting smaller date ranges? I am trying to pull a couple of years worth of data so if I can only get it a few days at a time it will take a lot of manual work.
I am currently using the free trial of a DB2 query tool - Razor SQL if that makes a difference, I can probably purchase different software if it would help. I am trying to get IBM's tool but for some reason it freezes during the download so I am still working on that. I have searched about this error but everything I see seems much more complex than what I am doing and I can't tell if it applies or not. Thanks in advance.
select *
from MyTable
where date_col between date '2014-01-01' and date '2014-01-31'
I stumbled at this error too, found out it is related to db2jcc.jar (type 4) driver.
Excerpt: If there are no items in the result set left (or to begin with), the Result set is closed automatically and therefore the Exception. Suggestion is to handle it in the application, perhaps in my case, I started checking if(rs.next()) but otherwise, there is a work around. Check out the source link below for how you can set some properties to Data source and avoid exception.
Source :
"Invalid operation: result set is closed" error with Data Server Driver for JDBC
In my case, i missed some properties in WAS, after add allowNextOnExhaustedResultSet the issue is fixed.
1.Log in to the WebSphere Application Server administration console.
2.Select Resources > JDBC > Data sources > Application Center DataSource name > Custom properties and click New.
3.In the Name field, enter allowNextOnExhaustedResultSet.
4.In the Value field, type 1.
5.Change the type to java.lang.Integer.
6.Click OK.
Sometimes you need also check whether resultSetHoldability properties exists. Details refer to here.
I encountered this failure also when ugrading from JDBC Type 2 driver (db2java.zip) JDBC type 4 driver (db2jcc4.jar)
Statement statement = results.getStatement();
if (statement != null)
{
connection = statement.getConnection(); // ** failed here
statement.close();
}
Solution was to check if the statement is closed or not as follows.
Changed to:
Statement statement = results.getStatement();
if (statement != null && !statement.isClosed()) {
{
connection = statement.getConnection();
statement.close();
}
Creating property bellow with type Integer it's worked for me:
allowNextOnExhaustedResultSet:
I had the same issue on WAS 7 so i had to add and change few this on Admin Console.
This TeamWorksRuntimeException exception should be fixed by applying APAR JR50863 which is available on top of BPM V8.5.5 or included on BPM V8.5 refresh pack 6.
For the case that the APAR does not solve the problem, try following workaround:
Log in to the WebSphere Application Server admin console
Select Resources > JDBC > Data sources > DataSource name (TeamWorksDB) > Custom properties and click New
In the Name field, enter downgradeHoldCursorsUnderXa
In the Value field, type true
Change the type to java.lang.Boolean
Click OK to save your changes
Select custom property resultSetHoldability
In the Value field, type 1
Click OK to save your changes
Source of the Answer : https://developer.ibm.com/answers/questions/194821/invalid-operation-result-set-is-closed-errorcode-4/
Restarting the app may fix the problem if connection pool lost session to Db2. If using Tomcat then connection pool property of 'testonBorrow' may reestablish the connection to Db2.
Is it possible to have one Redis Lua script hit more than one database? I currently have information of one type in DB 0 and information of another type in DB 1. My normal workflow is doing updates on DB 1 based on an API call along with meta information from DB 0. I'd love to do everything in one Lua script, but can't figure out how to hit multiple dbs. I'm doing this in Python using redis-py:
lua_script(keys=some_keys,
args=some_args,
client=some_client)
Since the client implies a specific db, I'm stuck. Ideas?
It is usually a wrong idea to put related data in different Redis databases. There is almost no benefit compared to defining namespaces by key naming conventions (no extra granularity regarding security, persistence, expiration management, etc ...). And a major drawback is the clients have to manually handle the selection of the correct database, which is error prone for clients targeting multiple databases at the same time.
Now, if you still want to use multiple databases, there is a way to make it work with redis-py and Lua scripting.
redis-py does not define a wrapper for the SELECT command (normally used to switch the current database), because of the underlying thread-safe connection pool implementation. But nothing prevents you to call SELECT from a Lua script.
Consider the following example:
$ redis-cli
SELECT 0
SET mykey db0
SELECT 1
SET mykey db1
The following script displays the value of mykey in the 2 databases from the same client connection.
import redis
pool = redis.ConnectionPool(host='localhost', port=6379, db=0)
r = redis.Redis(connection_pool=pool)
lua1 = """
redis.call("select", ARGV[1])
return redis.call("get",KEYS[1])
"""
script1 = r.register_script(lua1)
lua2 = """
redis.call("select", ARGV[1])
local ret = redis.call("get",KEYS[1])
redis.call("select", ARGV[2])
return ret
"""
script2 = r.register_script(lua2)
print r.get("mykey")
print script2( keys=["mykey"], args = [1,0] )
print r.get("mykey"), "ok"
print
print r.get("mykey")
print script1( keys=["mykey"], args = [1] )
print r.get("mykey"), "misleading !!!"
Script lua1 is naive: it just selects a given database before returning the value. Its usage is misleading, because after its execution, the current database associated to the connection has changed. Don't do this.
Script lua2 is much better. It takes the target database and the current database as parameters. It makes sure that the current database is reactivated before the end of the script, so that next command applied on the connection still run in the correct database.
Unfortunately, there is no command to guess the current database in the Lua script, so the client has to provide it systematically. Please note the Lua script must reset the current database at the end whatever happens (even in case of previous error), so it makes complex scripts cumbersome and awkward.