Basic Cache Operations
Getting an Instance of a Cache
All operations on a cache are performed through an instance of IgniteCache
.
You can obtain IgniteCache
for an existing cache, or you can create a cache dynamically.
Ignite ignite = Ignition.ignite();
// Obtain an instance of the cache named "myCache".
// Note that different caches may have different generics.
IgniteCache<Integer, String> cache = ignite.cache("myCache");
IIgnite ignite = Ignition.Start();
// Obtain an instance of cache named "myCache".
// Note that generic arguments are only for your convenience.
// You can work with any cache in terms of any generic arguments.
// However, attempt to retrieve an entry of incompatible type
// will result in exception.
ICache<int, string> cache = ignite.GetCache<int, string>("myCache");
IgniteConfiguration cfg;
cfg.springCfgPath = "/path/to/configuration.xml";
Ignite ignite = Ignition::Start(cfg);
// Obtain instance of cache named "myCache".
// Note that different caches may have different generics.
Cache<int32_t, std::string> cache = ignite.GetCache<int32_t, std::string>("myCache");
Creating Caches Dynamically
You can also create a cache dynamically:
Ignite ignite = Ignition.ignite();
CacheConfiguration<Integer, String> cfg = new CacheConfiguration<>();
cfg.setName("myNewCache");
cfg.setAtomicityMode(CacheAtomicityMode.TRANSACTIONAL);
// Create a cache with the given name if it does not exist.
IgniteCache<Integer, String> cache = ignite.getOrCreateCache(cfg);
Refer to the Cache Configuration section for the list of cache parameters.
IIgnite ignite = Ignition.Start();
// Create cache with given name, if it does not exist.
var cache = ignite.GetOrCreateCache<int, string>("myNewCache");
IgniteConfiguration cfg;
cfg.springCfgPath = "/path/to/configuration.xml";
Ignite ignite = Ignition::Start(cfg);
// Create a cache with the given name, if it does not exist.
Cache<int32_t, std::string> cache = ignite.GetOrCreateCache<int32_t, std::string>("myNewCache");
The methods that create a cache throw an org.apache.ignite.IgniteCheckedException
exception when called while the baseline topology is being changed.
javax.cache.CacheException: class org.apache.ignite.IgniteCheckedException: Failed to start/stop cache, cluster state change is in progress.
at org.apache.ignite.internal.processors.cache.GridCacheUtils.convertToCacheException(GridCacheUtils.java:1323)
at org.apache.ignite.internal.IgniteKernal.createCache(IgniteKernal.java:3001)
at org.apache.ignite.internal.processors.platform.client.cache.ClientCacheCreateWithNameRequest.process(ClientCacheCreateWithNameRequest.java:48)
at org.apache.ignite.internal.processors.platform.client.ClientRequestHandler.handle(ClientRequestHandler.java:51)
at org.apache.ignite.internal.processors.odbc.ClientListenerNioListener.onMessage(ClientListenerNioListener.java:173)
at org.apache.ignite.internal.processors.odbc.ClientListenerNioListener.onMessage(ClientListenerNioListener.java:47)
at org.apache.ignite.internal.util.nio.GridNioFilterChain$TailFilter.onMessageReceived(GridNioFilterChain.java:278)
at org.apache.ignite.internal.util.nio.GridNioFilterAdapter.proceedMessageReceived(GridNioFilterAdapter.java:108)
at org.apache.ignite.internal.util.nio.GridNioAsyncNotifyFilter$3.body(GridNioAsyncNotifyFilter.java:96)
at org.apache.ignite.internal.util.worker.GridWorker.run(GridWorker.java:119)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
You may want to retry the operation if you catch this exception.
Destroying Caches
To delete a cache from all cluster nodes, call the destroy()
method.
Ignite ignite = Ignition.ignite();
IgniteCache<Long, String> cache = ignite.cache("myCache");
cache.destroy();
var ignite = Ignition.ignite(); var cache = ignite.cache("myCache"); cache.destroy();
This API is not presently available for C++.
Atomic Operations
Once you get the instance of a cache, you can start performing get/put operations on it.
IgniteCache<Integer, String> cache = ignite.cache("myCache");
// Store keys in the cache (the values will end up on different cache nodes).
for (int i = 0; i < 10; i++)
cache.put(i, Integer.toString(i));
for (int i = 0; i < 10; i++)
System.out.println("Got [key=" + i + ", val=" + cache.get(i) + ']');
using (var ignite = Ignition.Start("examples/config/example-cache.xml"))
{
var cache = ignite.GetCache<int, string>("cache_name");
for (var i = 0; i < 10; i++)
{
cache.Put(i, i.ToString());
}
for (var i = 0; i < 10; i++)
{
Console.Write("Got [key=" + i + ", val=" + cache.Get(i) + ']');
}
}
IgniteConfiguration cfg;
cfg.springCfgPath = "/path/to/configuration.xml";
try
{
Ignite ignite = Ignition::Start(cfg);
Cache<int32_t, std::string> cache = ignite.GetOrCreateCache<int32_t, std::string>(CACHE_NAME);
// Store keys in the cache (the values will end up on different cache nodes).
for (int32_t i = 0; i < 10; i++)
{
cache.Put(i, std::to_string(i));
}
for (int i = 0; i < 10; i++)
{
std::cout << "Got [key=" << i << ", val=" + cache.Get(i) << "]" << std::endl;
}
}
catch (IgniteError& err)
{
std::cout << "An error occurred: " << err.GetText() << std::endl;
return err.GetCode();
}
Below are more examples of basic atomic operations:
// Put-if-absent which returns previous value.
String oldVal = cache.getAndPutIfAbsent(11, "Hello");
// Put-if-absent which returns boolean success flag.
boolean success = cache.putIfAbsent(22, "World");
// Replace-if-exists operation (opposite of getAndPutIfAbsent), returns previous
// value.
oldVal = cache.getAndReplace(11, "New value");
// Replace-if-exists operation (opposite of putIfAbsent), returns boolean
// success flag.
success = cache.replace(22, "Other new value");
// Replace-if-matches operation.
success = cache.replace(22, "Other new value", "Yet-another-new-value");
// Remove-if-matches operation.
success = cache.remove(11, "Hello");
using (var ignite = Ignition.Start("examples/config/example-cache.xml"))
{
var cache = ignite.GetCache<string, int>("cache_name");
// Put-if-absent which returns previous value.
var oldVal = cache.GetAndPutIfAbsent("Hello", 11);
// Put-if-absent which returns boolean success flag.
var success = cache.PutIfAbsent("World", 22);
// Replace-if-exists operation (opposite of getAndPutIfAbsent), returns previous value.
oldVal = cache.GetAndReplace("Hello", 11);
// Replace-if-exists operation (opposite of putIfAbsent), returns boolean success flag.
success = cache.Replace("World", 22);
// Replace-if-matches operation.
success = cache.Replace("World", 2, 22);
// Remove-if-matches operation.
success = cache.Remove("Hello", 1);
}
IgniteConfiguration cfg;
cfg.springCfgPath = "/path/to/configuration.xml";
Ignite ignite = Ignition::Start(cfg);
Cache<std::string, int32_t> cache = ignite.GetOrCreateCache<std::string, int32_t>("myNewCache");
// Put-if-absent which returns previous value.
int32_t oldVal = cache.GetAndPutIfAbsent("Hello", 11);
// Put-if-absent which returns boolean success flag.
boolean success = cache.PutIfAbsent("World", 22);
// Replace-if-exists operation (opposite of getAndPutIfAbsent), returns previous value.
oldVal = cache.GetAndReplace("Hello", 11);
// Replace-if-exists operation (opposite of putIfAbsent), returns boolean success flag.
success = cache.Replace("World", 22);
// Replace-if-matches operation.
success = cache.Replace("World", 2, 22);
// Remove-if-matches operation.
success = cache.Remove("Hello", 1);
Asynchronous Execution
Most of the cache operations have asynchronous counterparts that have the "Async" suffix in their names.
// a synchronous get
V get(K key);
// an asynchronous get
IgniteFuture<V> getAsync(K key);
// a synchronous get
TV Get(TK key);
// an asynchronous get
Task<TV> GetAsync(TK key);
This API is not presently available for C++.
The asynchronous operations return an object that represents the result of the operation. You can wait for the completion of the operation in either blocking or non-blocking manner.
To wait for the results in a non-blocking fashion, register a closure using the IgniteFuture.listen()
or IgniteFuture.chain()
method. The closure is called when the operation is completed.
IgniteCompute compute = ignite.compute();
// Execute a closure asynchronously.
IgniteFuture<String> fut = compute.callAsync(() -> "Hello World");
// Listen for completion and print out the result.
fut.listen(f -> System.out.println("Job result: " + f.get()));
class HelloworldFunc : IComputeFunc<string>
{
public string Invoke()
{
return "Hello World";
}
}
public static void AsynchronousExecution()
{
var ignite = Ignition.Start();
var compute = ignite.GetCompute();
//Execute a closure asynchronously
var fut = compute.CallAsync(new HelloworldFunc());
// Listen for completion and print out the result
fut.ContinueWith(Console.Write);
}
This API is not presently available for C++.
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