arez.component.internal.MemoizeCache Maven / Gradle / Ivy
package arez.component.internal;
import arez.ActionFlags;
import arez.Arez;
import arez.ArezContext;
import arez.Component;
import arez.ComputableValue;
import arez.Disposable;
import arez.Procedure;
import arez.SafeFunction;
import arez.Task;
import grim.annotations.OmitSymbol;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Stack;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import org.intellij.lang.annotations.MagicConstant;
import static org.realityforge.braincheck.Guards.*;
/**
* The class responsible for caching
*/
public final class MemoizeCache
implements Disposable
{
/**
* Functional interface for calculating memoizable value.
*
* @param The type of the returned value.
*/
@FunctionalInterface
public interface Function
{
/**
* Return calculated memoizable value.
*
* @param args the functions arguments.
* @return the value generated by function.
*/
T call( @Nonnull final Object... args );
}
/**
* Reference to the system to which this node belongs.
*/
@OmitSymbol( unless = "arez.enable_zones" )
@Nullable
private final ArezContext _context;
/**
* A human consumable prefix for computable values. It should be non-null if {@link Arez#areNamesEnabled()} returns
* true and null otherwise.
*/
@Nullable
@OmitSymbol( unless = "arez.enable_names" )
private final String _name;
/**
* The component that this memoize cache is contained within.
* This should only be set if {@link Arez#areNativeComponentsEnabled()} is true but can be null even if this is true.
*/
@OmitSymbol( unless = "arez.enable_native_components" )
@Nullable
private final Component _component;
/**
* The function memoized.
*/
@Nonnull
private final Function _function;
/**
* The cache of all the ComputableValue created for each unique combination of parameters.
*/
private final Map _cache = new HashMap<>();
/**
* The number of arguments passed to memoized function.
*/
private final int _argCount;
/**
* The flags passed to the created ComputableValues.
*/
private final int _flags;
/**
* The index of the next ComputableValue created.
* This is only used when creating unique names for ComputableValues.
*/
private int _nextIndex;
/**
* Flag indicating that the cache is currently being disposed.
*/
private boolean _disposed;
/**
* Create the Memoize method cache.
*
* @param context the context in which to create ComputableValue instances.
* @param component the associated native component if any. This should only be set if {@link Arez#areNativeComponentsEnabled()} returns true.
* @param name a human consumable prefix for computable values.
* @param function the memoized function.
* @param argCount the number of arguments expected to be passed to memoized function.
*/
public MemoizeCache( @Nullable final ArezContext context,
@Nullable final Component component,
@Nullable final String name,
@Nonnull final Function function,
final int argCount )
{
this( context, component, name, function, argCount, 0 );
}
/**
* Create the Memoize method cache.
*
* @param context the context in which to create ComputableValue instances.
* @param component the associated native component if any. This should only be set if {@link Arez#areNativeComponentsEnabled()} returns true.
* @param name a human consumable prefix for computable values.
* @param function the memoized function.
* @param argCount the number of arguments expected to be passed to memoized function.
* @param flags the flags that are used when creating ComputableValue instances. The only flags supported are flags defined in {@link ComputableValue.Flags} except for {@link ComputableValue.Flags#KEEPALIVE}, {@link ComputableValue.Flags#RUN_NOW} and {@link ComputableValue.Flags#RUN_LATER}.
*/
public MemoizeCache( @Nullable final ArezContext context,
@Nullable final Component component,
@Nullable final String name,
@Nonnull final Function function,
final int argCount,
@MagicConstant( flagsFromClass = ComputableValue.Flags.class ) final int flags )
{
if ( Arez.shouldCheckApiInvariants() )
{
apiInvariant( () -> Arez.areZonesEnabled() || null == context,
() -> "Arez-174: MemoizeCache passed a context but Arez.areZonesEnabled() is false" );
apiInvariant( () -> Arez.areNamesEnabled() || null == name,
() -> "Arez-0159: MemoizeCache passed a name '" + name + "' but Arez.areNamesEnabled() is false" );
apiInvariant( () -> argCount > 0,
() -> "Arez-0160: MemoizeCache constructed with invalid argCount: " + argCount +
". Expected positive value." );
final int mask = ComputableValue.Flags.PRIORITY_HIGHEST |
ComputableValue.Flags.PRIORITY_HIGH |
ComputableValue.Flags.PRIORITY_NORMAL |
ComputableValue.Flags.PRIORITY_LOW |
ComputableValue.Flags.PRIORITY_LOWEST |
ComputableValue.Flags.NO_REPORT_RESULT |
ComputableValue.Flags.AREZ_DEPENDENCIES |
ComputableValue.Flags.AREZ_OR_NO_DEPENDENCIES |
ComputableValue.Flags.AREZ_OR_EXTERNAL_DEPENDENCIES |
ComputableValue.Flags.OBSERVE_LOWER_PRIORITY_DEPENDENCIES |
ComputableValue.Flags.READ_OUTSIDE_TRANSACTION;
apiInvariant( () -> ( ~mask & flags ) == 0,
() -> "Arez-0211: MemoizeCache passed unsupported flags. Unsupported bits: " + ( ~mask & flags ) );
}
_context = Arez.areZonesEnabled() ? Objects.requireNonNull( context ) : null;
_component = Arez.areNativeComponentsEnabled() ? component : null;
_name = Arez.areNamesEnabled() ? Objects.requireNonNull( name ) : null;
_function = Objects.requireNonNull( function );
_argCount = argCount;
_flags = flags;
}
/**
* Return the result of the memoized function, calculating if necessary.
*
* @param args the arguments passed to the memoized function.
* @return the result of the memoized function.
*/
public T get( @Nonnull final Object... args )
{
if ( Arez.shouldCheckApiInvariants() )
{
apiInvariant( this::isNotDisposed,
() -> "Arez-0161: MemoizeCache named '" + _name + "' had get() invoked when disposed." );
}
return getComputableValue( args ).get();
}
@Override
public boolean isDisposed()
{
return _disposed;
}
@Override
public void dispose()
{
if ( !_disposed )
{
_disposed = true;
getContext().safeAction( Arez.areNamesEnabled() ? _name : null, () -> {
disposeMap( _cache, _argCount );
_cache.clear();
}, ActionFlags.NO_VERIFY_ACTION_REQUIRED );
}
}
@Nonnull
private ArezContext getContext()
{
return Arez.areZonesEnabled() ? Objects.requireNonNull( _context ) : Arez.context();
}
/**
* Traverse to leaf map elements and dispose all contained ComputableValue instances.
*/
@SuppressWarnings( "unchecked" )
private void disposeMap( @Nonnull final Map map, final int depth )
{
if ( 1 == depth )
{
for ( final Map.Entry entry : map.entrySet() )
{
final ComputableValue computableValue = (ComputableValue) entry.getValue();
computableValue.dispose();
}
}
else
{
for ( final Map.Entry entry : map.entrySet() )
{
disposeMap( (Map) entry.getValue(), depth - 1 );
}
}
}
/**
* Retrieve the computable value for specified parameters, creating it if necessary.
*
* @param args the arguments passed to the memoized function.
* @return the computable value instance for the specified args.
*/
@SuppressWarnings( "unchecked" )
@Nonnull
public ComputableValue getComputableValue( @Nonnull final Object... args )
{
if ( Arez.shouldCheckApiInvariants() )
{
apiInvariant( () -> args.length == _argCount,
() -> "Arez-0162: MemoizeCache.getComputableValue called with " + args.length +
" arguments but expected " + _argCount + " arguments." );
}
Map map = _cache;
final int size = args.length - 1;
for ( int i = 0; i < size; i++ )
{
map = (Map) map.computeIfAbsent( args[ i ], v -> new HashMap<>() );
}
ComputableValue computableValue =
(ComputableValue) map.computeIfAbsent( args[ size ], v -> createComputableValue( args ) );
if ( Disposable.isDisposed( computableValue ) )
{
computableValue = createComputableValue( args );
map.put( args[ size ], computableValue );
}
return computableValue;
}
/**
* Create computable value for specified parameters.
*
* @param args the arguments passed to the memoized function.
*/
@Nonnull
private ComputableValue createComputableValue( @Nonnull final Object... args )
{
final Component component = Arez.areNativeComponentsEnabled() ? _component : null;
final String name = Arez.areNamesEnabled() ? _name + "." + _nextIndex++ : null;
final Procedure onDeactivate = () -> disposeComputableValue( args );
final SafeFunction function = () -> _function.call( args );
return getContext().computable( component, name, function, null, onDeactivate, _flags );
}
/**
* Method invoked to dispose memoized value.
* This is called from deactivate hook so there should always by a cached value present
* and thus we never check for missing elements in chain.
*
* @param args the arguments originally passed to the memoized function.
*/
@SuppressWarnings( "unchecked" )
void disposeComputableValue( @Nonnull final Object... args )
{
if ( Arez.shouldCheckInvariants() )
{
invariant( () -> args.length == _argCount,
() -> "Arez-0163: MemoizeCache.disposeComputableValue called with " + args.length +
" argument(s) but expected " + _argCount + " argument(s)." );
}
if ( _disposed )
{
return;
}
final Stack> stack = new Stack<>();
stack.push( _cache );
final int size = args.length - 1;
for ( int i = 0; i < size; i++ )
{
stack.push( (Map) stack.peek().get( args[ i ] ) );
}
final ComputableValue computableValue = (ComputableValue) stack.peek().remove( args[ size ] );
if ( Arez.shouldCheckInvariants() )
{
invariant( () -> null != computableValue,
() -> "Arez-0193: MemoizeCache.disposeComputableValue called with args " + Arrays.asList( args ) +
" but unable to locate corresponding ComputableValue." );
}
assert null != computableValue;
getContext().task( Arez.areNamesEnabled() ? computableValue.getName() + ".dispose" : null,
computableValue::dispose,
Task.Flags.PRIORITY_HIGHEST | Task.Flags.DISPOSE_ON_COMPLETE | Task.Flags.NO_WRAP_TASK );
while ( stack.size() > 1 )
{
final Map map = stack.pop();
if ( map.isEmpty() )
{
stack.peek().remove( args[ stack.size() - 1 ] );
}
else
{
return;
}
}
}
@OmitSymbol
Map getCache()
{
return _cache;
}
@OmitSymbol
int getNextIndex()
{
return _nextIndex;
}
@OmitSymbol
int getFlags()
{
return _flags;
}
}
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