java-design-patterns | A cookbook of simple Java design patterns | Architecture library
kandi X-RAY | java-design-patterns Summary
kandi X-RAY | java-design-patterns Summary
A cookbook of commonly used Java design patterns based on examples from:. I'll be adding new patterns to the project on an ad-hoc basis. Each pattern is contained in its own package - the package-info will provide more details and the Test class will demonstrate how to use it. Any comments/bugs/better ways of doing things, send 'em my way.
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Top functions reviewed by kandi - BETA
- Execute a buy order
- Balance the exchange books
- Audits audit status for a trade
- Update market maker
- Update the latest market price of an observable
- Create a new buy order object
- Create a new buy order
- This method is called when the Market is updated
- This method is called to collect fund information about fund
- Get fund currency
- The list of the holdings of the person
- Returns a list of the holdings of this person
- Build a Product
- Build the contact details
- Makes a visitor visit this object
- Gets the holdings
- This method is used to execute an order book
- Convenience method to execute an order book
- The list of the holdings of the Bank account
- Build the customer
- This method returns the credit value of this component
- Override this method to process the review document
- Builds a Customer
- Creates a product
- Processes a document request
- This method is used to get the totalBalance for the Taxonomy
java-design-patterns Key Features
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Trending Discussions on java-design-patterns
QUESTION
I am a little confused as to why Optimistic Locking is actually safe. If I am checking the version at the time of retrieval with the version at the time of update, it seems like I can still have two requests enter the update block if the OS issues an interrupt and swaps the processes before the commit actually occurs. For example:
...ANSWER
Answered 2021-Mar-03 at 22:15Well... that's the optimistic part. The optimism is that it is safe. If you have to be certain it's safe, then that's not optimistic.
The example you show definitely is susceptible to a race condition. Not only because of thread scheduling, but also due to transaction isolation level.
A simple read in MySQL, in the default transaction isolation level of REPEATABLE READ, will read the data that was committed at the time your transaction started.
Whereas updating data will act on the data that is committed at the time of the update. If some other concurrent session has updated the row in the database in the meantime, and committed it, then your update will "see" the latest committed row, not the row viewed by your get method.
The way to avoid the race condition is to not be optimistic. Instead, force exclusive access to the record. Doveryai, no proveryai.
If you only have one app instance, you might use a critical section for this.
If you have multiple app instances, critical sections cannot coordinate other instances, so you need to coordinate in the database. You can do this by using pessimistic locking. Either read the record using a locking read query, or else you can use MySQL's user-defined locks.
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
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Install java-design-patterns
You can use java-design-patterns like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the java-design-patterns component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .
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