com.bigdata.rdf.sail.webapp

Class AbstractRestApiTask<T>

java.lang.Object

com.bigdata.rdf.task.AbstractApiTask<T>

com.bigdata.rdf.sail.webapp.AbstractRestApiTask<T>

Type Parameters:

T -

All Implemented Interfaces:

IReadOnly, IApiTask<T>, Callable<T>

Direct Known Subclasses:

AbstractDelegateRestApiTask

public abstract class AbstractRestApiTask<T>
extends AbstractApiTask<T>

Abstract base class for REST API methods. This class is compatible with a job-oriented concurrency control pattern.

Author:

Bryan Thompson

See Also:

HA doLocalAbort() should interrupt NSS requests and AbstractTasks , Concurrent unisolated operations against multiple KBs

Field Summary

Fields

Modifier and Type	Field and Description
protected javax.servlet.http.HttpServletRequest	req The HttpServletRequest.
protected javax.servlet.http.HttpServletResponse	resp The HttpServletResponse.
protected UUID	uuid The UUID associated with this task.

Fields inherited from class com.bigdata.rdf.task.AbstractApiTask

namespace, timestamp

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractRestApiTask(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp, String namespace, long timestamp)
protected	AbstractRestApiTask(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp, String namespace, long timestamp, boolean isGRSRequired)

Method Summary

Methods

Modifier and Type	Method and Description
protected void	buildResponse(int status, String mimeType, String content, NV... headers) Generate a response having the indicated http status code, mime type, and content.
void	flushAndClose() Flush and close the ServletOutputStream or PrintWriter depending on which was obtained.
OutputStream	getOutputStream() Return the ServletOutputStream associated with the request (and stash a copy).
PrintWriter	getWriter() Return the PrintWriter associated with the request (and stash a copy).
protected void	reportModifiedCount(long nmodified, long elapsed) Reports the mutation count and elapsed operation time as specified by the REST API for mutation operations.
String	toString()

Methods inherited from class com.bigdata.rdf.task.AbstractApiTask

getConnection, getIndexManager, getMutationCount, getNamespace, getQueryConnection, getQueryConnection, getTimestamp, getUnisolatedSailConnection, isGRSRequired, isReadOnly, setIndexManager, submitApiTask

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.concurrent.Callable

call

Field Detail

uuid

protected final UUID uuid

The UUID associated with this task. This is used to CANCEL a task.

See Also:

All REST API operations should be cancelable from both REST API and workbench

req

protected final javax.servlet.http.HttpServletRequest req

The HttpServletRequest.

resp

protected final javax.servlet.http.HttpServletResponse resp

The HttpServletResponse.

Constructor Detail

AbstractRestApiTask

protected AbstractRestApiTask(javax.servlet.http.HttpServletRequest req,
                   javax.servlet.http.HttpServletResponse resp,
                   String namespace,
                   long timestamp)

Parameters:

req - The HttpServletRequest.

resp - The HttpServletResponse.

namespace - The namespace of the target KB instance.

timestamp - The timestamp of the view of that KB instance.

AbstractRestApiTask

protected AbstractRestApiTask(javax.servlet.http.HttpServletRequest req,
                   javax.servlet.http.HttpServletResponse resp,
                   String namespace,
                   long timestamp,
                   boolean isGRSRequired)

Parameters:

req - The HttpServletRequest.

resp - The HttpServletResponse.

namespace - The namespace of the target KB instance.

timestamp - The timestamp of the view of that KB instance.

isGSRRequired - true iff the task requires a lock on the GRS index.

Method Detail

getOutputStream

public OutputStream getOutputStream()
                             throws IOException

Return the ServletOutputStream associated with the request (and stash a copy).

Throws:

IOException

IllegalStateException - per the servlet API if the writer has been requested already.

getWriter

public PrintWriter getWriter()
                      throws IOException

Return the PrintWriter associated with the request (and stash a copy).

Throws:

IOException

IllegalStateException - per the servlet API if the ServletOutputStream has been requested already.

flushAndClose

public void flushAndClose()
                   throws IOException

Flush and close the ServletOutputStream or PrintWriter depending on which was obtained.

Throws:

IOException

toString

public String toString()

Overrides:

toString in class AbstractApiTask<T>

reportModifiedCount

protected void reportModifiedCount(long nmodified,
                       long elapsed)
                            throws IOException

Reports the mutation count and elapsed operation time as specified by the REST API for mutation operations.

Note: When GROUP_COMMIT (#566) is enabled the http output stream MUST NOT be closed by this method. Doing so would permit the client to conclude that the operation was finished before the group commit actually occurs. This situation arises because the AbstractApiTask implementation has invoked conn.commit() and hence believes that it was successful, but the AbstractTask itself has not yet been through a checkpoint and the write set for the commit group has not yet been melded into a stable commit point. By NOT closing the output stream here we defer the signal to the client until control is returned to the servlet container layer, which does not occur until the task has finished executing and the group commit is done. The servlet container then closes the output stream and the client notices that the mutation operation is done and that its applied mutation is now visible to a client reading against that commit point. (Mind you, there might be other mutations in the same group commit or even in subsequent commits so the client does not have a strong guarantee that their mutation is visible in a post-commit read unless they are controlling all writers.)

Note: The other code path for signaling to the client that a mutation is done is SPARQL UPDATE. See that code for a similar caution.

Parameters:

nmodified - The number of modified triples/quads.

elapsed - The elapsed time for the operation.

Throws:

IOException

buildResponse

protected void buildResponse(int status,
                 String mimeType,
                 String content,
                 NV... headers)
                      throws IOException

Generate a response having the indicated http status code, mime type, and content.

Parameters:

status - The http status code.

mimeType - The MIME type of the response.

content - The content

headers - Zero or more headers to be included in the response.

Throws:

IOException

AssertionError - if the caller attempts to use this method for a non-success (2xx) outcome. The correct pattern is to throw an HttpOperationException instead once you are inside of an AbstractRestApiTask.