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From Denis Mekhanikov <dmekhani...@gmail.com>
Subject Re: Does IgniteCache.containsKey lock the key in a Transaction?
Date Thu, 22 Aug 2019 11:30:13 GMT
Yohan,

IgniteCache#containsKey(...) <https://ignite.apache.org/releases/latest/javadoc/org/apache/ignite/IgniteCache.html#containsKey-K->
locks a key under pessimistic transactions with REPEATABLE_READ isolation level, just like
a get().
And it doesn’t make servers send values back to a requesting node, so basically it does
what you need.

Denis

> On 19 Aug 2019, at 14:08, Yohan Fernando <Yohan.Fernando@tudor.com> wrote:
> 
> Hi Nattapon,
>  
> Unfortunately explicit locks cannot be used within transactions and an exception will
be thrown.
>  
> It seems the only way is to rely on implicit locks using calls like get() and containsKey().
I looked through the ignite source for these methods and it does appear like containsKey delegates
to the same call as get() but has a flag about whether to serialize or not so I assume that
containsKey might avoid serialization. However I’m not an expert on the Ignite codebase
so it would be good if someone can confirm that this is indeed the case.
>  
> Thanks
>  
> Yohan
>  
> From: nattapon <wrongite@gmail.com <mailto:wrongite@gmail.com>> 
> Sent: 19 August 2019 08:00
> To: user@ignite.apache.org <mailto:user@ignite.apache.org>
> Subject: Re: Does IgniteCache.containsKey lock the key in a Transaction?
>  
> Caution: This email originated from outside of Tudor.
>  
> Hi Yohan,
>  
> There is IgniteCache.lock(key) method described in https://apacheignite.readme.io/docs/distributed-locks
<https://urldefense.proofpoint.com/v2/url?u=https-3A__apacheignite.readme.io_docs_distributed-2Dlocks&d=DwMFaQ&c=lcVbikor4usg5Rj5OmznbA&r=m3tOHOhTDmqyOCq26PYainXMtahLsVWUQ4sqnN5broM&m=OI_UZ3gny3V8V5LQLeGQxF_GFdCwvZRHvxcHXzZ9tno&s=Bi2hfO-Sdhxidc_h2QGpmMRSfsEapHSmgLg9BH0nNbo&e=>
. Is it suited your requirement?
>  
> IgniteCache<String, Integer> cache = ignite.cache("myCache");
> 
> // Create a lock for the given key
> Lock lock = cache.lock("keyLock");
> try {
>     // Acquire the lock
>     lock.lock();
>   
>     cache.put("Hello", 11);
>     cache.put("World", 22);
> }
> finally {
>     // Release the lock
>     lock.unlock();
> }
>  
> Regards,
> Nattapon
>  
> On Fri, Aug 16, 2019 at 5:23 PM Yohan Fernando <Yohan.Fernando@tudor.com <mailto:Yohan.Fernando@tudor.com>>
wrote:
> Hi All, Does  IgniteCache.containsKey() lock the key in a Transaction similar to IgniteCache.get()
? Basically I want a lightweight call to lock the key without having to Serialize objects
from each node within a Transaction. 
>  
>  
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with its registered office at 10 New Burlington Street, London, W1S 3BE, United Kingdom
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