As listed here, Google Cloud Storage operations are split into 3 classes: A/B/Free. I'd like to know to which class does blob.exists() (testing the existence of a file) belongs? I would have guessed it belonged to the B class but then found that answer that gives me reasons to think that could be free.
I depends on whether the object is found or not, this document does mention what is on the answer you found as a note bellow the operations chart.
However, as the method is performing a get by judging from here, it should be considered as a B class operation in case that the object is found as it would not return a 307, 4xx, or 5xx.
Related
Cache2k looks like a very promising caching implementation. Unfortunately the documentation is very limited, which is why I need some help with the following issue. I am using the latest version 0.26-BETA.
According to the documentation the cache is supposed to be created like this:
Cache<String,String> c =
CacheBuilder.newCache(String.class, String.class).build();
String val = c.peek("something");
assertNull(val);
c.put("something", "hello");
val = c.get("something");
assertNotNull(val);
c.destroy();
Unfortunately at least 2 of these methods are deprecated, including the CacheBuilder class itself. I therefore tried creating the cache like this:
org.cache2k.Cache<String, Object> newCache = Cache2kBuilder.of(String.class, Object.class)
.name(cacheKey.toString())
.entryCapacity(100000)
.eternal(true)
.build();
This however throws the "java.lang.UnsupportedOperationException: loader not set" exception.
The question therefore is: how am I supposed to build the cache so that I do not get this exception?
EDIT:
This gives me the same exception:
org.cache2k.Cache<Object, Object> newCache =
CacheBuilder.newCache(Object.class, Object.class)
.eternal(true)
.build();
EDIT #2:
Just one more note: When I copy&paste the code from the wiki page I get an error - as can be seen in the image below.
With what jdk version are you testing? I'll try just removing the <> that are causing the problem for now.
Thanks very much in advance!
Michael
Cache2k looks like a very promising caching implementation.
Thanks :)
According to the documentation the cache is supposed to be created like this
There are new interfaces in place. The deprecated one is still there to support users of old cache2k versions. That will get cleared up in the next weeks. Sorry for the confusion.
Please take a look here for the latest getting started information:
https://github.com/cache2k/cache2k/blob/master/doc/src/docs/asciidoc/user-guide/sections/_start.adoc
This however throws the "java.lang.UnsupportedOperationException: loader not set" exception.
The question therefore is: how am I supposed to build the cache so that I do not get this exception?
Short answer: Either use cache.peek() or wait for 0.27, since then it is working with cache.get() transparently.
Longer answer: In our own applications I use cache.get() only when a loader is defined and cache.peek() when no loader is defined or when I want to inspect the cache only. Reserving cache.get() only for the read through usage, seemed like a good idea. However, I reasoned that it might be a caveat for new users, so I change that behavior and align it to other cache solutions.
Answer to Edit 2:
For an untyped cache use the factory method Cache2kBuilder.forUnkownTypes(). Constructing the anonymous class is only needed for specific types.
ThreadLocal-like class that keeps its value through Future.map/Future.flatMap is extremely useful to trace request, for example, for logging.
Is there existing abstraction in Scala library to serve as such Local?
Is there a way to attach such Local to ExecutionContext.global?
Here is a blog entry where someone describes using scala.util.DynamicVariable and a custom scala.concurrent.ExecutionContext to capture and manage it: http://stevenskelton.ca/threadlocal-variables-scala-futures/
And here's is another blog entry describing how Hootsuite does something similar: http://code.hootsuite.com/logging-contextual-info-in-an-asynchronous-scala-application/
The details of the Request's with() implementation of RequestFactory in GWT is a bit unclear to me. See here for the official documentation.
Question 1:
When querying the server, RequestFactory does not automatically
populate relations in the object graph. To do this, use the with()
method on a request and specify the related property name as a String.
Does this mean that if the Entity at the server uses Lazy Fetching, the returned EntityProxy will have all the requested objects specified in with()? It seems a bit odd to instantiate the whole object graph of the Object server side, to only send a small piece to the client.
Question 2:
Does req.with("foo").with("foo"); do the same as req.with("foo"); ?
Question 3:
Does req.with("foo").with("bar"); do the same as req.with("foo","bar"); ?
NOTE: I'm having a really hard time finding the implementation details of with() in the source code and the API doesn't help me either.
Question 1:
It probably depends on your server side implemenation.
The with invocation will only make sure that the corresponding getter (getFoo()) is called shortly before the RF call returns to the client.
That's the reason why you also have to make sure to use an OpenSessionInView pattern, otherwise you might run into NullPointeterExceptions.
Question 2:
I guess the Request<T> implements a builder pattern.
The end-result will be the same.
However I am not sure if the getter() will be called twice or if the with method will check if the getter is already requested.
Question 3:
Yes it's the same.
As a sidenote. You can use req.with("foo.bar").
On the backend this will lead to a getFoo().getBar() call.
I've read some documentation and downloaded samples but I still got a question.
In most sample, the GIN module uses something like :
bind(MainActivityMapper.class);
bind(VerticalMasterActivityMapper.class);
I don't understand what it does? If I remove it from the sample code, everything works perfectly.
Thanks for any answer.
Someone pointed me to the GUICE page : http://google-guice.googlecode.com/git/javadoc/com/google/inject/Binder.html
There is no reason for it to be different in Gin.
Here is what it says for this particular case :
This statement does essentially nothing; it "binds the
class to itself" and does not change Guice's default behavior. You may
still want to use this if you prefer your Module class to serve as an
explicit manifest for the services it provides. Also, in rare cases,
Guice may be unable to validate a binding at injector creation time
unless it is given explicitly.
Note: I'm not sure wether or not I should Accept my own answer, so I'll leave it as is.
I tried searching on google, and got literally no results when trying to figure out what this means. My console is logging:
objc[17048]: Class _NSZombie_GEOLatLng is implemented in both ?? and ??. One of the two will be used. Which one is undefined.
objc[17048]: Class _NSZombie_GEOLatLng is implemented in both ?? and ??. One of the two will be used. Which one is undefined.
objc[17048]: Class _NSZombie_GEOLocation is implemented in both ?? and ??. One of the two will be used. Which one is undefined.
objc[17048]: Class _NSZombie_GEOLocation is implemented in both ?? and ??. One of the two will be used. Which one is undefined.
Anyone seen this before, or have any idea what it means, what's causing it, and if it's a problem?
I've seen it. Specifically, on OS X - but the cause should be the same. GEOLocation (and others) is defined in two images which are loaded into the process.
If that were a class you wrote, the class' symbols are defined in multiple object files (would likely be a linker error though…), in the linked libraries, loaded bundles, or some combination of - when code may be loaded dynamically.
If it's not a class you wrote (or synthesized), file a bug with the creator of the class.
It's also possible that the class is defined in your app, and also defined in a linked library. In that event, you would need to change the name of your class.
It is definitely a problem. The class (with that name) is being loaded into the objc runtime twice, and there are no guarantees as to which implementation will be returned when an instance is created since objc uses a flat namespace.
In this case, the class exists in the system frameworks so... send it to the bug reporter - it deserves be fixed quickly.
This is a harmless warning that occurs when you have enabled zombie warnings in the build scheme. You can ignore it.
I had this obscure message and noticed that a NIB had been removed from the project, but code was still using it. You may want to check if any resources have been removed from the bundle that are still in use.