I need to get a list of chunks after sharding inside my Java code. My code is simple and looks like this:
Mongo m = new Mongo( "localhost" , 27017 );
DB db = m.getDB( "admin" );
Object cr = db.eval("db.printShardingStatus()", 1);
A call of eval() returns an error:
Exception in thread "main" com.mongodb.CommandResult$CommandFailure: command failed [$eval]: { "serverUsed" : "localhost/127.0.0.1:27017" , "errno" : -3.0 , "errmsg" : "invoke failed: JS Error: ReferenceError: printShardingStatus is not defined src/mongo/shell/db.js:891" , "ok" : 0.0}
at com.mongodb.CommandResult.getException(CommandResult.java:88)
at com.mongodb.CommandResult.throwOnError(CommandResult.java:134)
at com.mongodb.DB.eval(DB.java:340)
at org.sm.mongodb.MongoTest.main(MongoTest.java:35)
And, really, if we look into the code of db.js, in line 891 there is a call to a method printShardingStatus() that is not defined inside a file. Inside of sh.status() method in utils_sh.js file, there is even a comment:
// TODO: move the actual commadn here
Important to mention, when I run these commands in mongo command line, everything works properly!
My questions are:
Is there any other possibility of getting a full sharding status within Java code? (eg. with DB.command() method)
If not, any other suggestions how to avoid my problem?
Many of the shell's helper functions are not available for server-side code execution. In the case of printShardingStatus(), it makes sense because there isn't a console to use for printing output and you'd rather have a string returned. Thankfully, you should be able to pull up the source of the shell function and reimplement it in your application (e.g. concatenating a returned string instead of printing directly).
$ mongo
MongoDB shell version: 2.2.0
connecting to: test
> db.printShardingStatus
function (verbose) {
printShardingStatus(this.getSiblingDB("config"), verbose);
}
So, let's look at the printShardingStatus() function...
> printShardingStatus
function (configDB, verbose) {
if (configDB === undefined) {
configDB = db.getSisterDB("config");
}
var version = configDB.getCollection("version").findOne();
// ...
}
Before turning all of the output statements into string concatenation, you'd want to make sure the other DB methods are all available to you. Performance-wise, I think the best option is to port the innards of this function to Java and avoid server-side JS evaluation altogether. If you dive deeper into the printShardingStatus() function, you'll see it's just issuing find() on the config database along with some group() queries.
If you do want to stick with evaluating JS and would rather not keep this code within your Java application, you can also look into storing JS functions server-side.
Have you deployed a shard cluster properly?
If so, you could connect to a mongo database that has sharding enabled.
Try calling the method db.printShardingStatus() with a that database within the mongo shell and see what happens.
Apparently the Javascript function 'printShardingStatus' is only available for the mongo shell and not for execution with server commands, to see the code start mongo.exe and type only 'printShardingStatus' and press enter.
In this case writing an extension method would be the best for solving this...
Javascript way of printing output of MongoDB query to a file
1] create a javascript file
test.js
cursor = db.printShardingStatus();
while(cursor.hasNext()){
printjson(cursor.next());
}
2] run
mongo admin --quiet test.js > output.txt
Related
I'm trying to redefine a method at runtime using javassist, but I'm running into some issues on the last step, because of the weird requirements I have for this:
I can't require the user to add startup flags
My code will necessarily run after the class has already been defined/loaded
My code looks like this:
val cp = ClassPool.getDefault()
val clazz = cp.get("net.minecraft.world.item.ItemStack")
val method = clazz.getDeclaredMethod(
"a",
arrayOf(cp.get("net.minecraft.world.level.block.state.IBlockData"))
)
method.setBody(
"""
{
double destroySpeed = this.c().a(this, $1);
if (this.s()) {
return destroySpeed * this.t().k("DestroySpeedMultiplier");
} else {
return destroySpeed;
}
}
""".trimIndent()
)
clazz.toClass(Items::class.java)
(I'm dealing with obfuscated method references, hence the weird names)
However, calling .toClass() causes an error as there are then two duplicate classes on the class loader - and to my knowledge there's no way to unload a single class.
My next port of call to update the class was to use the attach API and an agent, but that requires a startup flag to be added (on Java 9+, I'm running J17), which I can't do given my requirements. I have the same problem trying to load an agent on startup.
I have tried patching the server's jar file itself by using .toBytecode(), but I didn't manage to write the new class file to the jar - this method sounds promising, so it's absolutely on the table to restart the server after patching the jar.
Is there any way I can get this to work with my requirements? Or is there any alternative I can use to change a method's behavior?
I am new to gradle and need to write a task for scheduling MarkLogic backup.
So, I want to invoke an XQuery module that uses a config XML for getting details for backup.
So I tried this :
task mlBackupTask(type: com.marklogic.gradle.task.ServerEvalTask) {
def client = hubConfig.newStagingClient()
println client
//DatabaseClient client = DatabaseClientFactory.newClient(host,portno,new DatabaseClientFactory.DigestAuthContext(username, password))
ServerEvaluationCall invoker = client.newServerEval();
String result = invoker.modulePath("/admin/create-backup.xqy").addVariable("config-name", "dev").evalAs(String.class);
}
I tried both :
hubConfig.newStagingClient()
DatabaseClientFactory.newClient(host,portno,new DatabaseClientFactory.DigestAuthContext(username, password))
This doesn't work and just give this error :
Execution failed for task ':mlBackupTask'.
java.lang.NullPointerException (no error message)
Could someone please help out on this?
Start with the docs at https://github.com/marklogic-community/ml-gradle/wiki/Writing-your-own-task . "hubConfig.newStagingClient()" will only work if you're using DHF, as hubConfig is specific to DHF.
Also, I think based on your code, what you really want is to use MarkLogicTask. The purpose of ServerEvalTask is to allow you to write a single line of JS or XQuery code. It looks like you want to write multiple lines of code, given a DatabaseClient. If so, use MarkLogicTask, and also put your code in a "doLast" block as shown in the docs.
I'm trying to execute bash script using karate. I'm able to execute the script from karate-config.js and also from .feature file. I'm also able to pass the arguments to the script.
The problem is, that if the script fails (exits with something else than 0) the test execution continues and finishes as succesfull.
I found out that when the script echo-es something then i can access it as a result of the script so I could possibly echo the exit value and do assertion on it (in some re-usable feature), but this seems like a workaround rather than a valid clean solution. Is there some clean way of accessing the exit code without echo-ing it? Am I missing on something?
script
#!/bin/bash
#possible solution
#echo 3
exit 3;
karate-config.js
var result = karate.exec('script.sh arg1')
feture file
def result = karate.exec('script.sh arg1')
Great timing. We very recently did some work for CLI testing which I am sure you can use effectively. Here is a thread on Twitter: https://twitter.com/maxandersen/status/1276431309276151814
And we have just released version 0.9.6.RC4 and new we have a new karate.fork() option that returns an instance of Command on which you can call exitCode
Here's an example:
* def proc = karate.fork('script.sh arg1')
* proc.waitSync()
* match proc.exitCode == 0
You can get more ideas here: https://github.com/intuit/karate/issues/1191#issuecomment-650087023
Note that the argument to karate.fork() can take multiple forms. If you are using karate.exec() (which will block until the process completes) the same arguments work.
string - full command line as seen above
string array - e.g. ['script.sh', 'arg1']
json where the keys can be
line - string (OR)
args - string array
env - optional environment properties (as JSON)
redirectErrorStream - boolean, true by default which means Sys.err appears in Sys.out
workingDir - working directory
useShell - default false, auto-prepend cmd /c or sh -c depending on OS
And since karate.fork() is async, you need to call waitSync() if needed as in the example above.
Do provide feedback and we can tweak further if needed.
EDIT: here's a very advanced example that shows how to listen to the process output / log, collect the log, and conditionally exit: fork-listener.feature
Another answer which can be a useful reference: Conditional match based on OS
And here's how to use cURL for advanced HTTP tests ! https://stackoverflow.com/a/73230200/143475
In case you need to do a lot of local file manipulation, you can use the karate.toJavaFile() utility so you can convert a relative path or a "prefixed" path to an absolute path.
* def file = karate.toJavaFile('classpath:some/file.txt')
* def path = file.getPath()
I have created an application using py4j that makes it possible to save data from python in to SQL database using a java application,everything works so fine when i run the JVM as an application and it actually saves the data. But when i run the code in a server it gives me back an exception.Therfore i thought maybe my server(Wildfly) and Py4j are using the same port so i changed the default py4j port as the turotial suggested and this is how the python sides looks like after modification:
from py4j.java_gateway import JavaGateway, GatewayParameters
gateway = JavaGateway(GatewayParameters(port=25335))
testBD = gateway.entry_point
DBin = gateway.jvm.com.packtpub.wflydevelopment.ch.Application(10,3) #calling constructor
testBD.create(DBin)
but i m still having an exception:
Traceback (most recent call last):
File "C:\Users\user\Desktop\test.py", line 4, in
DBin = gateway.jvm.com.packtpub.wflydevelopment.ch.Application(10,3)
File "C:\Users\user\AppData\Local\Programs\Python\Python35-32\lib\site-packages\py4j-0.9-py3.5.egg\py4j\java_gateway.py", line 1185, in getattr
answer = self._gateway_client.send_command(
AttributeError: 'GatewayParameters' object has no attribute 'send_command'
Any suggestions would be very much appreciated.
I got the answer from bartdag from the issue at https://github.com/bartdag/py4j/issues/180, he pointed out that specifying the GatewayParameter instance to the argument "gateway_parameters" it works.
# This produces the error
gateway = JavaGateway(GatewayParameters(address='192.168.99.100', port=25333))
But adding the argument name makes it work:
# This solves it the error
gateway = JavaGateway(gateway_parameters=GatewayParameters(address='192.168.99.100', port=25333))
i want to take backup of postgres database using java. I am using following code for this
but this is not working and not generating dump.
String pgDump = "C:\\Program Files\\PostgreSQL\\9.2\\bin\\pg_dump";
String dumpFile = "D:\\test\\"+ tenant.getTenantAsTemplate()+".sql";
String sql = pgDump+" -h localhost -U postgres -P postgres " + tenant.getTenantAsTemplate()+" > "+dumpFile;
Process p = Runtime.getRuntime().exec(sql);
int time = p.waitFor();
System.out.println("time is "+time);
if(time == 0){
System.out.println("backup is created");
}
else{
System.out.println("fail to create backup");
}
Here i am getting time is 1.
This is also operating system dependent and we need also pg_dump. is there any other way to generate backup of database without pg_dump?
please reply soon.
No, there is no way to generate a database backup without pg_dump, using the regular SQL connection. It's a bit of an FAQ, but the people who want the feature never step up to do the work to implement the feature in PostgreSQL.
I guess technically you could use a replication connection to do a physical base backup like pg_basebackup does, but that's not really what you want, requires copying all databases on the machine, and would be a lot of work.
You should use the String[] form of Runtime.exec as I mentioned in a related answer regarding pg_restore.
You must also check the process exit value to see if it terminated successfully or not, and you must be careful to handle, not just swallow, any exceptions thrown.
Your code fails to check the exit value, and I think it's probably generating a malformed command that's failing with a non-zero exit code, probably because you are not correctly quoting the path to pg_dump. To see what's wrong, print the final assembled command line, you'll see something like:
C:\Program Files\PostgreSQL\9.2\bin\pg_dump -h localhost ....
which cmd.exe will split into:
c:\Program
Files\postgresql\9.2\bin\pg_dump
-h
localhost
... etc
See the problem?
Do not just quote the path to pg_dump to work around this. Use the String[] form of exec and you won't have to, plus it'll work correctly for other things like accidental %environmentvars% in paths.