Task environment selectors are used by task factories to determine which build environment is suitable for their execution. They do this selection by examining the environment properties of the build environment and deciding they are appropriate for the associated task.
The implementations are required to report the environment properties which resulted in successful selection of the build environment.
Implementations of TaskExecutionEnvironmentSelector should not be stateful objects.
Implementations are required to be Externalizable, and/or in any other way RMI-transferrable, as methods of this interface cannot be called through RMI.
During the environment selection process, the environment selector instance will be transferred to the machine which the given build environment resides on. This behaviour is applied when build clusters are used.
Implementations should adhere to the contract specified by equals(
public boolean | Checks if this environment selector would find suitable the same environments as the parameter given the same
circumstances. |
public int | hashCode() Returns a hash code value for the object. |
public default boolean | Checks if the environment selection can only run on the local build environment. |
public EnvironmentSelectionResult | isSuitableExecutionEnvironment( Checks if the argument build environment is suitable for running the associated task with this selector. |
public static TaskExecutionEnvironmentSelector | multi( Gets a task environment selector that satisfies all the argument selectors. |
public static TaskExecutionEnvironmentSelector | multi( Gets a task environment selector that satisfies all the argument selectors. |
Indicates whether some other object is "equal to" this one.
The equals
method implements an equivalence relation on non-null object references:
- It is reflexive: for any non-null reference value
x
,x.equals(x)
should returntrue
. - It is symmetric: for any non-null reference values
x
andy
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any non-null reference values
x
,y
, andz
, ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
. - It is consistent: for any non-null reference values
x
andy
, multiple invocations ofx.equals(y)
consistently returntrue
or consistently returnfalse
, provided no information used inequals
comparisons on the objects is modified. - For any non-null reference value
x
,x.equals(null)
should returnfalse
.
The equals
method for class Object
implements the most discriminating possible equivalence
relation on objects; that is, for any non-null reference values x
and y
, this method returns
true
if and only if x
and y
refer to the same object (x == y
has the value
true
).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden,
so as to maintain the general contract for the hashCode
method, which states that equal objects must have
equal hash codes.
true
if this object is the same as the obj argument; false
otherwise.
The general contract of hashCode
is:
- Whenever it is invoked on the same object more than once during an execution of a Java application, the
hashCode
method must consistently return the same integer, provided no information used inequals
comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. - If two objects are equal according to the
equals(Object)
method, then calling thehashCode
method on each of the two objects must produce the same integer result. - It is not required that if two objects are unequal according to the
Object.equals(
Object) method, then calling thehashCode
method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by class Object
does return distinct
integers for distinct objects. (This is typically implemented by converting the internal address of the object
into an integer, but this implementation technique is not required by the Java™ programming language.)
The local build environment is the one the build execution was started on. It is also known as the coordinator.
If this method returns true
, the build execution will not attempt to check remote clusters for
suitability. The method can be used if the environment selection is dependent on the local build environment.
The default implementation returns false
.
true
if the environment selection is restricted to the local environmnet.Implementers of this method should determine its results only based on the environment properties of the build environment. Implementations of this interface are required to return these properties in the result object with their corresponding values.
Implicit dependencies will be reported for the qualifier environment properties for the task if the environment
is deemed to be suitable.
Note: The implicit dependencies will not be reported for inner tasks.
Implementations cannot use SakerEnvironment.getEnvironmentIdentifier() to deem a given environment suitable. Doing so would make the builds dependent on random numbers, therefore greatly reducing reproducibility. Tasks can select already known environments to execute inner tasks on via setting the allowed environment identifiers of the inner task parameters.
null
if the environment is
not suitable for invoking the associated task.The returned task execution environment selector will check all arguments for suitability.
null
.The returned task execution environment selector will check all arguments for suitability.
null
.