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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA.
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<title>NSDistantObject class reference</title>
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$Date: 2002/02/03 17:21:20 $ $Revision: 1.41 $
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$Date: 2005/02/22 11:22:44 $ $Revision: 1.65 $
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#include <base/preface.h>
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#include <base/DistributedObjects.h>
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#include <Foundation/NSLock.h>
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#include <Foundation/NSPort.h>
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#include <Foundation/NSMethodSignature.h>
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#include <Foundation/NSException.h>
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#include <Foundation/NSObjCRuntime.h>
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#include <Foundation/NSInvocation.h>
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#include "GNUstepBase/preface.h"
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#include "GNUstepBase/DistributedObjects.h"
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#include "Foundation/NSDebug.h"
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#include "Foundation/NSLock.h"
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#include "Foundation/NSPort.h"
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#include "Foundation/NSMethodSignature.h"
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#include "Foundation/NSException.h"
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#include "Foundation/NSObjCRuntime.h"
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#include "Foundation/NSInvocation.h"
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#define DO_FORWARD_INVOCATION(_SELX, _ARG1) \
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#define DO_FORWARD_INVOCATION(_SELX, _ARG1) ({ \
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sig = [self methodSignatureForSelector: @selector(_SELX)]; \
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inv = [NSInvocation invocationWithMethodSignature: sig]; \
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[inv setSelector: @selector(_SELX)]; \
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[inv setTarget: self]; \
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[inv setArgument: (void*)&_ARG1 atIndex: 2]; \
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[self forwardInvocation: inv]; \
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[inv getReturnValue: &m]
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inv = [NSInvocation invocationWithMethodSignature: sig]; \
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[inv setSelector: @selector(_SELX)]; \
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[inv setTarget: self]; \
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[inv setArgument: (void*)&_ARG1 atIndex: 2]; \
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[self forwardInvocation: inv]; \
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[inv getReturnValue: &m]; \
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NSWarnLog(@"DO_FORWARD_INVOCATION failed, got nil signature for '%@'.", \
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NSStringFromSelector(@selector(_SELX))); \
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static int debug_proxy = 0;
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@defs(NSDistantObject)
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@interface Object (NSConformsToProtocolNamed)
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- (BOOL) _conformsToProtocolNamed: (char*)aName;
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@interface NSObject (NSConformsToProtocolNamed)
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- (BOOL) _conformsToProtocolNamed: (char*)aName;
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* Evil hack ... if a remote system wants to know if we conform
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* to a protocol we pretend we have a local protocol with the same name.
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@implementation Object (NSConformsToProtocolNamed)
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- (BOOL) _conformsToProtocolNamed: (char*)aName
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p.protocol_name = (char*)aName;
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return [self conformsTo: (Protocol*)&p];
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@implementation NSObject (NSConformsToProtocolNamed)
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- (BOOL) _conformsToProtocolNamed: (char*)aName
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p.protocol_name = (char*)aName;
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return [self conformsToProtocol: (Protocol*)&p];
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@interface NSConnection (DistantObjectHacks)
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- (BOOL) includesProxyForTarget: (unsigned)target;
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- (void) addLocalObject: (id)obj;
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- (void) addProxy: (id)obj;
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- (void) aquireProxyForTarget: (unsigned)target;
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- (NSDistantObject*) retainOrAddLocal: (NSDistantObject*)aProxy
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forObject: (id)anObject;
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- (NSDistantObject*) retainOrAddProxy: (NSDistantObject*)aProxy
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forTarget: (unsigned)aTarget;
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- (void) removeProxy: (id)obj;
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- (void) vendLocal: (NSDistantObject*)aProxy;
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/* This is the proxy tag; it indicates where the local object is,
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and determines whether the reply port to the Connection-where-the-
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proxy-is-local needs to encoded/decoded or not. */
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PROXY_LOCAL_FOR_RECEIVER = 0,
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PROXY_LOCAL_FOR_SENDER,
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PROXY_REMOTE_FOR_BOTH
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- (id) initWithCoder: (NSCoder*)aCoder
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id decoder_connection;
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if ([aCoder isKindOfClass: [NSPortCoder class]] == NO)
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[NSException raise: NSGenericException
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format: @"NSDistantObject objects only decode with "
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@"NSPortCoder class"];
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decoder_connection = [(NSPortCoder*)aCoder connection];
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NSAssert(decoder_connection, NSInternalInconsistencyException);
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/* First get the tag, so we know what values need to be decoded. */
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[aCoder decodeValueOfObjCType: @encode(typeof(proxy_tag))
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case PROXY_LOCAL_FOR_RECEIVER:
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* This was a proxy on the other side of the connection, but
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* Lookup the target handle to ensure that it exists here.
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* Return a retained copy of the local target object.
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[aCoder decodeValueOfObjCType: @encode(typeof(target))
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NSLog(@"Receiving a proxy for local object 0x%x "
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@"connection 0x%x\n", target, (gsaddr)decoder_connection);
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if (![[decoder_connection class] includesLocalTarget: target])
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[NSException raise: @"ProxyDecodedBadTarget"
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format: @"No local object with given target (0x%x)",
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o = [decoder_connection includesLocalTarget: target];
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NSLog(@"Local object is 0x%x (0x%x)\n",
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(gsaddr)o, (gsaddr)o ? o->_object : 0);
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return o ? RETAIN(o->_object) : nil;
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case PROXY_LOCAL_FOR_SENDER:
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* This was a local object on the other side of the connection,
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* but here it's a proxy object. Get the target address, and
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* send [NSDistantObject +proxyWithTarget:connection:]; this will
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* return the proxy object we already created for this target, or
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* create a new proxy object if necessary.
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[aCoder decodeValueOfObjCType: @encode(typeof(target))
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NSLog(@"Receiving a proxy, was local 0x%x connection 0x%x\n",
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target, (gsaddr)decoder_connection);
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return RETAIN([NSDistantObject proxyWithTarget: target
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connection: decoder_connection]);
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case PROXY_REMOTE_FOR_BOTH:
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* This was a proxy on the other side of the connection, and it
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* will be a proxy on this side too; that is, the local version
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* of this object is not on this host, not on the host the
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* NSPortCoder is connected to, but on a *third* host.
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* This is why I call this a "triangle connection". In addition
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* to decoding the target, we decode the OutPort object that we
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* will use to talk directly to this third host. We send
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* [NSConnection +newForInPort:outPort:ancestorConnection:]; this
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* will either return the connection already created for this
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* inPort/outPort pair, or create a new connection if necessary.
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NSDistantObject *result;
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NSConnection *proxy_connection;
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NSPort *proxy_connection_out_port = nil;
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unsigned intermediary;
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* There is an object on the intermediary host that is keeping
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* that hosts proxy for the original object retained, thus
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* ensuring that the original is not released. We create a
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* proxy for that intermediate proxy. When we release this
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* proxy, the intermediary will be free to release it's proxy
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* and the original can then be released. Of course, by that
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* time we will have obtained our own proxy for the original
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[aCoder decodeValueOfObjCType: @encode(typeof(intermediary))
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[NSDistantObject proxyWithTarget: intermediary
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connection: decoder_connection];
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* Now we get the target number and port for the orignal object
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* and (if necessary) get the originating process to retain the
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[aCoder decodeValueOfObjCType: @encode(typeof(target))
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[aCoder decodeValueOfObjCType: @encode(id)
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at: &proxy_connection_out_port];
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NSAssert(proxy_connection_out_port, NSInternalInconsistencyException);
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# If there already exists a connection for talking to the
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* out port, we use that one rather than creating a new one from
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* our listening port.
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* First we try for a connection from our receive port,
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* Then we try any connection to the send port
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* Finally we resort to creating a new connection - we don't
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* release the newly created connection - it will get released
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* automatically when no proxies are left on it.
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proxy_connection = [[decoder_connection class]
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connectionWithReceivePort: [decoder_connection receivePort]
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sendPort: proxy_connection_out_port];
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NSLog(@"Receiving a triangle-connection proxy 0x%x "
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@"connection 0x%x\n", target, (gsaddr)proxy_connection);
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NSAssert(proxy_connection != decoder_connection,
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NSInternalInconsistencyException);
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NSAssert([proxy_connection isValid],
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NSInternalInconsistencyException);
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* If we don't already have a proxy for the object on the
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* remote system, we must tell the other end to retain its
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* local object for our use.
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if ([proxy_connection includesProxyForTarget: target] == NO)
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[proxy_connection retainTarget: target];
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result = RETAIN([NSDistantObject proxyWithTarget: target
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connection: proxy_connection]);
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* Finally - we have a proxy via a direct connection to the
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* originating server. We have also created a proxy to an
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* intermediate object - but this proxy has not been retained
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* and will therefore go away when the current autorelease
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/* xxx This should be something different than NSGenericException. */
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[NSException raise: NSGenericException
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format: @"Bad proxy tag"];
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[NSException raise: NSGenericException
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format: @"NSDistantObject decodes from placeholder"];
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* Initialises and returns a proxy associated with aConnection
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* which will hold a reference to the local object anObject.
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- (id) initWithLocal: (id)anObject connection: (NSConnection*)aConnection
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NSDistantObject *new_proxy;
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NSAssert([aConnection isValid], NSInternalInconsistencyException);
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* If there already is a local proxy for this target/connection
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* combination, don't create a new one, just return the old one.
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if ((new_proxy = [aConnection localForObject: anObject]))
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* We don't need to retain the oibject here - the connection
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* will retain the proxies local object if necessary (and release it
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* when all proxies referring to it have been released).
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* We register this proxy with the connection using it.
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_object = RETAIN(anObject);
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_connection = RETAIN(aConnection);
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[_connection addLocalObject: self];
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self = [_connection retainOrAddLocal: self forObject: anObject];
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NSLog(@"Created new local=0x%x object 0x%x target 0x%x connection 0x%x\n",
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struct objc_method_description* mth;
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mth = [_protocol descriptionForInstanceMethod: aSelector];
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/* Older gcc versions may not initialise Protocol objects properly
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* so we have an evil hack which checks for a known bad value of
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* the class pointer, and uses an internal function
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* (implemented in NSObject.m) to examine the protocol contents
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* without sending any ObjectiveC message to it.
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if ((int)GSObjCClass(_protocol) == 0x2)
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extern struct objc_method_description*
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GSDescriptionForInstanceMethod();
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mth = GSDescriptionForInstanceMethod(_protocol, aSelector);
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mth = [_protocol descriptionForInstanceMethod: aSelector];
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mth = [_protocol descriptionForClassMethod: aSelector];
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if ((int)GSObjCClass(_protocol) == 0x2)
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extern struct objc_method_description*
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GSDescriptionForClassMethod();
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mth = GSDescriptionForClassMethod(_protocol, aSelector);
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mth = [_protocol descriptionForClassMethod: aSelector];
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types = mth->types;
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return [NSMethodSignature signatureWithObjCTypes: types];
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return [NSMethodSignature signatureWithObjCTypes: types];
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#if defined(USE_FFCALL) || defined(USE_LIBFFI)
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retframe = [self forward: _cmd : args];
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m = retframe_id(retframe);
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types = [m methodType];
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return [NSMethodSignature signatureWithObjCTypes: types];
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if ([m isProxy] == YES)
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const char *types = [m methodType];
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m = [NSMethodSignature signatureWithObjCTypes: types];
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* <p>A key method for Distributed Objects performance. This sets the
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* a protocol that the distant object referred to by the proxy should
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* conform to. When messages in that protocol are sent to the proxy,
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* the proxy knows that it does not need to ask the remote object for
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* the method siagnature in order to send the message to it, but can
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* send the message straight away based on the local method signature
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* information obtained from the protocol.
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* if ([anObj isProxy] == YES)
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* [anObj setProtocolForProxy: @protocol(MyProtocol)];
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* <p>It is <em>highly recommended</em> that you make use of this facility,
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* but you must beware that versions of the compiler prior to 3.3 suffer a
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* serious bug with respect to the @protocol directive. If the protocol
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* referred to is not declared and implemented in the file where @protocol
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* is used to refer to the protocol by name, a runtime error will occur
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* when you try to use it.
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* <p>Beware, if you don't use this method to set the protocol, the system
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* might well ask the remote process for method signature information, and
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* the remote process might get it <em>wrong</em>. This is because the
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* class of the remote object needs to have been declared to conform to the
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* protocol in order for it to know about any protocol qualifiers (the
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* keywords <code>bycopy, byref, in, out, inout,</code> and
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* <code>oneway</code>). If the author of the server process forgot to do
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* this, the type information returned from that process may not be what
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* The class of the server object should be declared like this ...
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* @interface MyServerClass : NSObject <MyProtocol>
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- (void) setProtocolForProxy: (Protocol*)aProtocol
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_protocol = aProtocol;
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NSLog(@"retain count for connection (0x%x) is now %u\n",
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(gsaddr)_connection, [_connection retainCount]);
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* A proxy for local object does not retain it's target - the
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* NSConnection class does that for us - so we need not release it.
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* A proxy for local object retains its target - so we release it.
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* For a local object the connection also retains this proxy, so we
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* can't be deallocated unless we are already removed from the
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* connection, and there is no need to remove self from connection.
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* A proxy retains it's connection so that the connection will
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* continue to exist as long as there is a something to use it.
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* A proxy has a nil local object, and retains it's connection so
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* that the connection will continue to exist as long as there is
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* a something to use it.
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* So we release our reference to the connection here just as soon
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* as we have removed ourself from the connection.
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if (_object == nil)
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[_connection removeProxy: self];
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RELEASE(_connection);
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- (id) awakeAfterUsingCoder: (NSCoder*)aDecoder
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static inline BOOL class_is_kind_of (Class self, Class aClassObject)
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for (class = self; class!=Nil; class = class_get_super_class(class))
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for (class = self; class!=Nil; class = GSObjCSuper(class))
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if (class==aClassObject)
added
removed
Source/NSDistantObject.m
