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Is the != check thread safe?
...g/Object;
ALOAD 0
GETFIELD test/Test1.a : Ljava/lang/Object;
IF_ACMPEQ L1
...
as we can see it loads field a to local vars twice, it's a non-atomic operation, if a was changed in between by another thread comparison may produce false.
Also, memory visibility problem is relevant here...
Ruby on Rails: How do I add a not null constraint to an existing column using a migration?
In my Rails (3.2) app, I have a bunch of tables in my database but I forgot to add a few not null constraints. I've googled around but I can't find how to write a migration which adds not null to an existing column.
...
What is Lazy Loading?
...:
...
@property
def total(self):
if not hasattr(self, "_total"):
self._total = self.quantity \
+ sum(bi.quantity for bi in self.borroweditem_set.all())
return self._total
Basically, I have an Item class which represents an item in our inven...
force Maven to copy dependencies into target/lib
...ocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>groupId</groupId>
<artifactId>artifactId</artifactId>
<version>1.0</version>
<dependencies>...
Improve INSERT-per-second performance of SQLite
... versions of SQLite - Consider a less paranoid journal mode (pragma journal_mode). There is NORMAL, and then there is OFF, which can significantly increase insert speed if you're not too worried about the database possibly getting corrupted if the OS crashes. If your application crashes the data sho...
Reusable library to get human readable version of file size?
...o require a library" issue by a straightforward implementation:
def sizeof_fmt(num, suffix='B'):
for unit in ['','Ki','Mi','Gi','Ti','Pi','Ei','Zi']:
if abs(num) < 1024.0:
return "%3.1f%s%s" % (num, unit, suffix)
num /= 1024.0
return "%.1f%s%s" % (num, 'Yi', s...
How to convert / cast long to String?
I just created sample BB app, which can allow to choose the date.
8 Answers
8
...
Check whether or not the current thread is the main thread
...be executed on the main thread, you can:
- (void)someMethod
{
dispatch_block_t block = ^{
// Code for the method goes here
};
if ([NSThread isMainThread])
{
block();
}
else
{
dispatch_async(dispatch_get_main_queue(), block);
}
}
...
Generating a random & unique 8 character string using MySQL
...tions
if the seed is an INT32
So we use @AndreyVolk's or @GordonLinoff's approach, but with a seeded RAND:
e.g. Assumin id is an AUTO_INCREMENT column:
INSERT INTO vehicles VALUES (blah); -- leaving out the number plate
SELECT @lid:=LAST_INSERT_ID();
UPDATE vehicles SET numberplate=concat(
su...
Scala: write string to file in one statement
....write(Paths.get("file.txt"), "file contents".getBytes(StandardCharsets.UTF_8))
I think this is by far the simplest and easiest and most idiomatic way, and it does not need any dependencies sans Java itself.
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