CollectionPolicy

```
public interface CollectionPolicy
```
The interface for a garbage collection policy. All sizes are in bytes.

Nested Class Summary

Nested Classes
Modifier and Type Interface and Description

static class CollectionPolicy.Options

Nested Classes
Modifier and Type	Interface and Description
`static class`	`CollectionPolicy.Options`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`void`	`ensureSizeParametersInitialized()` Ensures that size parameters have been computed and methods like `CollectionPolicy.getMaximumHeapSize()` provide reasonable values, but do not force a recomputation of the size parameters like `CollectionPolicy.updateSizeParameters()`.
`org.graalvm.word.UnsignedWord`	`getCurrentHeapCapacity()` The current limit for the size of the entire heap, which is less than or equal to `CollectionPolicy.getMaximumHeapSize()`.
`static CollectionPolicy`	`getInitialPolicy()`
`static String`	`getInitialPolicyName()`
`org.graalvm.word.UnsignedWord`	`getMaximumFreeAlignedChunksSize()` The maximum number of bytes that should be kept readily available for allocation or copying during collections.
`org.graalvm.word.UnsignedWord`	`getMaximumHeapSize()` The hard limit for the size of the entire heap.
`org.graalvm.word.UnsignedWord`	`getMaximumYoungGenerationSize()` The maximum capacity of the young generation, comprising eden and survivor spaces.
`static int`	`getMaxSurvivorSpaces(Integer userValue)`
`org.graalvm.word.UnsignedWord`	`getMinimumHeapSize()` The minimum heap size, for inclusion in diagnostic output.
`String`	`getName()`
`org.graalvm.word.UnsignedWord`	`getSurvivorSpacesCapacity()` The total capacity of all survivor-from spaces of all ages, equal to the size of all survivor-to spaces of all ages.
`int`	`getTenuringAge()` The age at which objects should currently be promoted to the old generation, which is between 1 (straight from eden) and the number of survivor spaces + 1.
`void`	`onCollectionBegin(boolean completeCollection, long requestingNanoTime)` Called at the beginning of a collection, in the safepoint operation.
`void`	`onCollectionEnd(boolean completeCollection, GCCause cause)` Called before the end of a collection, in the safepoint operation.
`boolean`	`shouldCollectCompletely(boolean followingIncrementalCollection)` At a safepoint, decides whether to do a complete collection (returning `true`) or an incremental collection (returning `false`).
`boolean`	`shouldCollectOnAllocation()` During a slow-path allocation, determines whether to trigger a collection.
`static boolean`	`shouldCollectYoungGenSeparately(boolean defaultValue)`
`void`	`updateSizeParameters()` (Re)computes minimum/maximum/initial sizes of space based on the available physical memory and current runtime option values.

- Method Detail
  - getInitialPolicyName
```
static String getInitialPolicyName()
```
  - getInitialPolicy
```
static CollectionPolicy getInitialPolicy()
```
  - getMaxSurvivorSpaces
```
static int getMaxSurvivorSpaces(Integer userValue)
```
  - shouldCollectYoungGenSeparately
```
static boolean shouldCollectYoungGenSeparately(boolean defaultValue)
```
  - getName
```
String getName()
```
  - ensureSizeParametersInitialized
```
void ensureSizeParametersInitialized()
```
    Ensures that size parameters have been computed and methods like CollectionPolicy.getMaximumHeapSize() provide reasonable values, but do not force a recomputation of the size parameters like CollectionPolicy.updateSizeParameters().
  - updateSizeParameters
```
void updateSizeParameters()
```
    (Re)computes minimum/maximum/initial sizes of space based on the available physical memory and current runtime option values. This method can be called directly or after a slow-path allocation (of a TLAB or a large object) and so allocation is allowed, but may trigger a collection.
  - shouldCollectOnAllocation
```
boolean shouldCollectOnAllocation()
```
    During a slow-path allocation, determines whether to trigger a collection. Returning true will initiate a safepoint during which CollectionPolicy.shouldCollectCompletely(boolean) will be called followed by the collection.
  - shouldCollectCompletely
```
boolean shouldCollectCompletely(boolean followingIncrementalCollection)
```
    At a safepoint, decides whether to do a complete collection (returning true) or an incremental collection (returning false).
    
    Parameters:
    
    followingIncrementalCollection - whether an incremental collection has just finished in the same safepoint. Implementations would typically decide whether to follow up with a full collection based on whether enough memory was reclaimed.
  - getCurrentHeapCapacity
```
org.graalvm.word.UnsignedWord getCurrentHeapCapacity()
```
    The current limit for the size of the entire heap, which is less than or equal to CollectionPolicy.getMaximumHeapSize(). NOTE: this can currently be exceeded during a collection while copying objects in the old generation.
  - getMaximumHeapSize
```
org.graalvm.word.UnsignedWord getMaximumHeapSize()
```
    The hard limit for the size of the entire heap. Exceeding this limit triggers an OutOfMemoryError. NOTE: this can currently be exceeded during a collection while copying objects in the old generation.
  - getMaximumYoungGenerationSize
```
org.graalvm.word.UnsignedWord getMaximumYoungGenerationSize()
```
    The maximum capacity of the young generation, comprising eden and survivor spaces.
  - getMinimumHeapSize
```
org.graalvm.word.UnsignedWord getMinimumHeapSize()
```
    The minimum heap size, for inclusion in diagnostic output.
  - getSurvivorSpacesCapacity
```
org.graalvm.word.UnsignedWord getSurvivorSpacesCapacity()
```
    The total capacity of all survivor-from spaces of all ages, equal to the size of all survivor-to spaces of all ages. In other words, when copying during a collection, up to 2x this amount can be used for surviving objects.
  - getMaximumFreeAlignedChunksSize
```
org.graalvm.word.UnsignedWord getMaximumFreeAlignedChunksSize()
```
    The maximum number of bytes that should be kept readily available for allocation or copying during collections.
  - getTenuringAge
```
int getTenuringAge()
```
    The age at which objects should currently be promoted to the old generation, which is between 1 (straight from eden) and the number of survivor spaces + 1.
  - onCollectionBegin
```
void onCollectionBegin(boolean completeCollection,
                       long requestingNanoTime)
```
    Called at the beginning of a collection, in the safepoint operation.
  - onCollectionEnd
```
void onCollectionEnd(boolean completeCollection,
                     GCCause cause)
```
    Called before the end of a collection, in the safepoint operation.

Interface CollectionPolicy

Nested Class Summary

Method Summary

Method Detail

getInitialPolicyName

getInitialPolicy

getMaxSurvivorSpaces

shouldCollectYoungGenSeparately

getName

ensureSizeParametersInitialized

updateSizeParameters

shouldCollectOnAllocation

shouldCollectCompletely

getCurrentHeapCapacity

getMaximumHeapSize

getMaximumYoungGenerationSize

getMinimumHeapSize

getSurvivorSpacesCapacity

getMaximumFreeAlignedChunksSize

getTenuringAge

onCollectionBegin

onCollectionEnd