jetbrains.exodus.env

Interface ContextualStore

All Superinterfaces:

Store

public interface ContextualStore
extends Store

ContextualStore is a Store created by ContextualEnvironment. Just like ContextualEnvironment, it is aware of transaction started in current thread. ContextualStore overloads all Store's methods with the ones that don't accept transaction instance.

See Also:

ContextualEnvironment, Transaction, Store

Method Summary

Modifier and Type	Method and Description
boolean	add(@NotNull ByteIterable key, @NotNull ByteIterable value) Adds key/value pair to the ContextualStore if the key doesn't exist.
long	count()
boolean	delete(@NotNull ByteIterable key) For stores without key duplicates, deletes single key/value pair and returns true if a pair was deleted.
boolean	exists(@NotNull ByteIterable key, @NotNull ByteIterable value) Checks if specified key/value pair exists in the ContextualStore.
@Nullable ByteIterable	get(@NotNull ByteIterable key) For stores without key duplicates, it returns not-null value or null if the key doesn't exist.
@NotNull ContextualEnvironment	getEnvironment()
Cursor	openCursor() Opens cursor over the @{code Store}.
boolean	put(@NotNull ByteIterable key, @NotNull ByteIterable value) Puts specified key/value pair into the ContextualStore and returns the result.
void	putRight(@NotNull ByteIterable key, @NotNull ByteIterable value) Can be used if it is a priori known that the key is definitely greater than any other key in the ContextualStore.

Methods inherited from interface jetbrains.exodus.env.Store

add, close, count, delete, exists, get, getConfig, getName, openCursor, put, putRight

Method Detail

getEnvironment

@NotNull
@NotNull ContextualEnvironment getEnvironment()

Specified by:

getEnvironment in interface Store

Returns:

environment which the store was opened for

get

@Nullable
@Nullable ByteIterable get(@NotNull
                                     @NotNull ByteIterable key)

For stores without key duplicates, it returns not-null value or null if the key doesn't exist. For stores with key duplicates, it returns the smallest not-null value associated with the key or null if no one exists.

Parameters:

key - requested key

Returns:

not-null value if key.value pair with the specified key exists, otherwise null

exists

boolean exists(@NotNull
               @NotNull ByteIterable key,
               @NotNull
               @NotNull ByteIterable value)

Checks if specified key/value pair exists in the ContextualStore.

Parameters:

key - key

value - value

Returns:

true if the key/value pair exists in the ContextualStore

put

boolean put(@NotNull
            @NotNull ByteIterable key,
            @NotNull
            @NotNull ByteIterable value)

Puts specified key/value pair into the ContextualStore and returns the result. For stores with key duplicates, it returns true if the pair didn't exist in the ContextualStore. For stores without key duplicates, it returns true if the key didn't exist or the new value differs from the existing one.

	With duplicates	Without duplicates
The key exists	Adds pair, if the value didn't exist	Overwrites value
The key doesn't exist	Adds pair	Adds pair

Parameters:

key - not null key

value - not null value

Returns:

true if specified pair was added or value by the key was overwritten.

putRight

void putRight(@NotNull
              @NotNull ByteIterable key,
              @NotNull
              @NotNull ByteIterable value)

Can be used if it is a priori known that the key is definitely greater than any other key in the ContextualStore. In that case, no search is been done before insertion, so putRight() can perform several times faster than put(ByteIterable, ByteIterable). It can be useful for auto-generated keys.

Parameters:

key - key

value - value

add

boolean add(@NotNull
            @NotNull ByteIterable key,
            @NotNull
            @NotNull ByteIterable value)

Adds key/value pair to the ContextualStore if the key doesn't exist. For stores with and without key duplicates, it returns true if and only if the key doesn't exists. So it never overwrites value of existing key.

	With duplicates	Without duplicates
The key exists	Returns false	Returns false
The key doesn't exist	Adds pair, returns true	Adds pair, returns true

Parameters:

key - key

value - value

Returns:

true if key/value pair was added

delete

boolean delete(@NotNull
               @NotNull ByteIterable key)

For stores without key duplicates, deletes single key/value pair and returns true if a pair was deleted. For stores with key duplicates, it deletes all pairs with the given key and returns true if any was deleted. To delete particular key/value pair, use cursors.

Parameters:

key - key

Returns:

true if a key/value pair was deleted.

count

long count()

Returns:

the number of key/value pairs in the ContextualStore

openCursor

Cursor openCursor()

Opens cursor over the @{code Store}. Returned instance can only be used in current thread.

Returns:

cursor