NetNews Usenet Archive 1993 #3

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Path: sparky!uunet!portal!lll-winken!taurus.cs.nps.navy.mil!taygeta.oc.nps.navy.mil!skip From: skip@taygeta.oc.nps.navy.mil (Skip Carter) Newsgroups: comp.lang.c++ Subject: Re: Objects in shared memory Message-ID: <C1HAwM.3qv@taurus.cs.nps.navy.mil> Date: 26 Jan 93 20:43:33 GMT References: <1993Jan19.082043.4341@dxcern.cern.ch> Sender: news@taurus.cs.nps.navy.mil Reply-To: skip@taygeta.oc.nps.navy.mil (Skip Carter) Organization: Naval Postgraduate School, Monterey Lines: 998 I tried to e-mail this but it bounced... ---- Cut Here and unpack ---- #!/bin/sh # shar: Shell Archiver (v1.22) # # # # # Run the following text with /bin/sh to create: # Classes.list # Readme.sm # Makefile # sharmem.cpp # sharmem.hpp # persist.cpp # smem.cpp # smema.cpp # smemb.cpp # if test -r s2_seq_.tmp then echo "Must unpack archives in sequence!" next=`cat s2_seq_.tmp`; echo "Please unpack part $next next" exit 1; fi echo "x - extracting Classes.list (Text)" sed 's/^X//' << 'SHAR_EOF' > Classes.list && X X X The following is a list of C++ classes that I have written and X am distributing by request to those that want them. X X X Derivs Calculates the first derivative of a single X parameter function by using Richardson Extrapolation. X This class is a C++ translation of an Ada package X given in the May 1991 issue of Computer Language . X X Kalman A general purpose Kalman filter class for optimal X estimation of a dynamical system. X X X Model, Map, Ode, Runge X X A family of classes that allows the treatement of X iterative maps and ordinary differential equations in X a unified manner. The ordinary differential equations X are solved using the class Runge which is a C++ adaptation X of the code given in: X W.H. Press, B.P. Flannery, S.A. Teukolsky and W.T. X Vetterling, Numerical Recipes: The Art of Scientific X Computing, Cambridge Univ. Press, New York, 1986 X These classes were the example classes described in X my recent Computer Language article: X The Evolution of a C++ programmer, Computer Language, X V. 9, No. 8, August 1992 X X X MonteIntegrator, Quasi X X A Monte Carlo function integrator and its supporting X random number generator. The random number generator X is a quasi-random (as opposed to a pseudo-random) number X generator, this gives the integrator a 1/N convergence X rate (as opposed to 1/Sqrt(N) ). Can integrate functions X up to 5 dimensions (this limit is due to the quasi random X number generator). X X X X Shared A Unix Shared Memory object base class. When this X class is inherited by other classes then the derived X class becomes a shared memory object that can be X accessed by multiple processes. These objects can be X persistant. X X SimAnneal A general purpose Simulated Annealing class, for X estimating optimum parameters of complicated functions X or systems. X X X X X X Everett (Skip) Carter Phone: 408-646-3318 FAX: 408-646-2712 X Naval Postgraduate School INTERNET: skip@taygeta.oc.nps.navy.mil X Dept. of Oceanography, Code OC/CR UUCP: ...!uunet!taygeta!skip X Monterey, CA. 93943 TELEMAIL: s.carter/omnet X X X X (Note: after 12 Dec 1992 the phone exchanges will change from 646 to 656) SHAR_EOF chmod 0644 Classes.list || echo "restore of Classes.list fails" echo "x - extracting Readme.sm (Text)" sed 's/^X//' << 'SHAR_EOF' > Readme.sm && X Shared memory/persistant objects X X The class Shared is a limited shared memory object that will also X allow persistant objects. X X Each object is instantiated in a new shared memory segment which is X a system wide (limited) resource. If the object is not deleted, it X will persist until the system is rebooted. This can be exploited X purposely in order to get persistant objects (as in persist.cpp). X X Objects that contain pointers or references to other objects or X variables that are not in shared memory will not work. Also virtual X methods cannot be used. X X X X The following code demonstrates of the use of shared memory: X X smem A single program that creates child processes X by forking. The processes use shared memory X for refering to a common object X X X smema/smemb Two independent programs that use shared memory X for a common object. Start smema first, then X start smemb (which gets the handle info from a file X created by smemb). When semaphores are NOT used, X start up smema in the background or from another window X and immediately start smemb (smema just waits for a while X and then assumes that there is valid data in the object). X X X X persist c Creates an object in shared memory X X X persist r Reads (and removes an object in shared memory that X was created with persist r). X X X X X X See the comments in sharmem.hpp and in the demo code. X X X X X Everett (Skip) Carter Phone: 408-646-3318 FAX: 408-646-2712 X Naval Postgraduate School INTERNET: skip@taygeta.oc.nps.navy.mil X Dept. of Oceanography, Code OC/CR UUCP: ...!uunet!taygeta!skip X Monterey, CA. 93943 TELEMAIL: s.carter/omnet X SHAR_EOF chmod 0644 Readme.sm || echo "restore of Readme.sm fails" echo "x - extracting Makefile (Text)" sed 's/^X//' << 'SHAR_EOF' > Makefile && X# Makefile for misc C++ code X# XHOME = /usr/skip XCLIB = $(HOME)/clib XCPPLIB = $(HOME)/cpplib XCLASSDIR = $(HOME)/classlib X# X# X# XCC = cc XCFLAGS = -O -I$(HOME) -I. XCPFLAGS = $(CFLAGS) XCPP = CC X# X# The suffix for C++ code XC++ = c++ X# X# XXFLAGS = -I/usr/include/bsd -DXTFUNCPROTO XLFLAGS = -lm X# X# XXLIBS = -lXm -lXt -lX11 -lbsd X# X# use the appropriate version XSEMAPHORE = XSEMFLAG = X# X#SEMAPHORE = semaphore.o X#SEMFLAG = -DUSE_SEMAPHORES X# X# X# =========================================================================== X# X# XEXPORT_SOURCES = derivs.hpp derivs.cpp sharmem.cpp sharmem.hpp map.cpp model.cpp \ X ode.cpp runge.cpp map.hpp model.hpp ode.hpp runge.hpp quasi.cpp quasi.hpp \ X standio.cpp standio.hpp getargs.h getargs.c stoi.c monteint.hpp \ X monteint.cpp comment.cpp comment.hpp timestamp.hpp timestamp.cpp X# Xall: derivkit sharmemkit modelkit mckit comkit X X# X# The test applications X# X# Xmctest: mctest.$(C++) monteint.o quasi.o standio.o getargs.o stoi.o X $(CPP) $(CPFLAGS) -o mctest mctest.$(C++) monteint.o quasi.o standio.o getargs.o stoi.o -lm X Xmodriver: modriver.$(C++) model.o map.o ode.o runge.o X $(CPP) $(CPFLAGS) -o modriver modriver.$(C++) model.o map.o ode.o runge.o -lm X Xsmem: smem.$(C++) sharmem.o $(SEMAPHORE) X $(CPP) $(CPFLAGS) $(SEMFLAG) smem.$(C++) sharmem.o $(SEMAPHORE) -o smem X Xsmema: smema.$(C++) sharmem.o $(SEMAPHORE) X $(CPP) $(CPFLAGS) $(SEMFLAG) smema.$(C++) sharmem.o $(SEMAPHORE) -o smema X Xsmemb: smemb.$(C++) sharmem.o $(SEMAPHORE) X $(CPP) $(CPFLAGS) $(SEMFLAG) smemb.$(C++) sharmem.o $(SEMAPHORE) -o smemb X Xpersist: persist.$(C++) sharmem.o X $(CPP) $(CPFLAGS) persist.$(C++) sharmem.o -o persist X X# X Xsigtest: X $(CC) $(CFLAGS) -o sigtest sigtest.c X# X# X# ============================================================================ X# X# Xclean: X -rm -f $(EXPORT_SOURCES) X -rm -f *.o *.bak *~ X X# X# X# X# The source distribution kits X# X# Xcomment.cpp: $(CLASSDIR)/comment.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/comment.c++ > comment.cpp X Xcomment.hpp: $(CLASSDIR)/comment.hpp X cp $(CLASSDIR)/comment.hpp comment.hpp X Xderivs.cpp: $(CLASSDIR)/derivs.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/derivs.c++ > derivs.cpp X Xderivs.hpp: $(CLASSDIR)/derivs.hpp X cp $(CLASSDIR)/derivs.hpp derivs.hpp X Xgetargs.c: $(CLIB)/getargs.c X cp $(CLIB)/getargs.c getargs.c X Xgetargs.h: $(CLIB)/getargs.h X cp $(CLIB)/getargs.h getargs.h X Xmap.hpp: $(CLASSDIR)/map.hpp X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/map.hpp > map.hpp X Xmap.cpp: $(CLASSDIR)/map.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/map.c++ > map.cpp X Xmodel.hpp: $(CLASSDIR)/model.hpp X cp $(CLASSDIR)/model.hpp model.hpp X Xmodel.cpp: $(CLASSDIR)/model.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/model.c++ > model.cpp X Xmonteint.hpp: $(CLASSDIR)/monteint.hpp X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/monteint.hpp > monteint.hpp X Xmonteint.cpp: $(CLASSDIR)/monteint.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/monteint.c++ > monteint.cpp X Xode.hpp: $(CLASSDIR)/ode.hpp X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/ode.hpp > ode.hpp X Xode.cpp: $(CLASSDIR)/ode.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/ode.c++ > ode.cpp X Xquasi.hpp: $(CLASSDIR)/quasi.hpp X cp $(CLASSDIR)/quasi.hpp quasi.hpp X Xquasi.cpp: $(CLASSDIR)/quasi.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/quasi.c++ > quasi.cpp X Xrunge.hpp: $(CLASSDIR)/runge.hpp X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/runge.hpp > runge.hpp X Xrunge.cpp: $(CLASSDIR)/runge.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/runge.c++ > runge.cpp X X Xsharmem.hpp: $(CLASSDIR)/sharmem.hpp X cp $(CLASSDIR)/sharmem.hpp sharmem.hpp X Xsharmem.cpp: $(CLASSDIR)/sharmem.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/sharmem.c++ > sharmem.cpp X Xstandio.hpp: $(CLASSDIR)/standio.hpp X cp $(CLASSDIR)/standio.hpp standio.hpp X Xstandio.cpp: $(CLASSDIR)/standio.c++ X cp $(CLASSDIR)/standio.c++ standio.cpp X Xstoi.c: $(CLIB)/stoi.c X cp $(CLIB)/stoi.c stoi.c X Xtimestamp.cpp: $(CLASSDIR)/timestamp.c++ X sed s/"<classlib\/"/"<"/g < $(CLASSDIR)/timestamp.c++ > timestamp.cpp X Xtimestamp.hpp: $(CLASSDIR)/timestamp.hpp X cp $(CLASSDIR)/timestamp.hpp timestamp.hpp X XSHAR_SOURCE_CODE = Readme.sm Makefile sharmem.cpp sharmem.hpp persist.cpp smem.cpp \ X smema.cpp smemb.cpp X XMODEL_SOURCE_CODE = Makefile map.cpp map.hpp model.cpp model.hpp ode.cpp ode.hpp \ X runge.cpp runge.hpp modriver.cpp X XMC_SOURCE_CODE = Readme.mc Makefile monteint.hpp monteint.cpp quasi.hpp quasi.cpp \ X standio.cpp standio.hpp getargs.h getargs.c stoi.c mctest.cpp X# X# Xderivkit: derivs.sh01 X Xsharmemkit: sharmem.sh01 X Xmodelkit: model.sh01 X Xmckit: monte.sh01 X Xcomkit: comkit.sh01 X Xderivs.sh01: derivs.hpp derivs.cpp X shar2 -v -c -l64 -oderivs.sh Classes.list derivs.hpp derivs.cpp X Xsharmem.sh01: $(SHAR_SOURCE_CODE) X shar2 -v -c -l64 -osharmem.sh Classes.list $(SHAR_SOURCE_CODE) X Xmodel.sh01: $(MODEL_SOURCE_CODE) X shar2 -v -c -l64 -omodel.sh Classes.list $(MODEL_SOURCE_CODE) X Xmonte.sh01: $(MC_SOURCE_CODE) X shar2 -v -c -l64 -omonte.sh Classes.list $(MC_SOURCE_CODE) X Xcomkit.sh01: comment.hpp comment.cpp timestamp.hpp timestamp.cpp challenge1.cpp X shar2 -v -c -l64 -ocomkit.sh comment.hpp comment.cpp timestamp.hpp \ X timestamp.cpp challenge1.cpp X X# X# Generics X# X#.asm.o: X# masm $< /ML; X# X.SUFFIXES : X.SUFFIXES : .cpp .cxx .cpp .c .h .o X X.cpp.o: X $(CPP) $(CPFLAGS) -c $*.cpp X X.cxx.o: X $(CPP) $(CPFLAGS) -c $*.cxx X X.c++.o: X $(CPP) $(CPFLAGS) -c $*.c++ X X.c.o: X $(CC) $(CFLAGS) -c $*.c X SHAR_EOF chmod 0666 Makefile || echo "restore of Makefile fails" echo "x - extracting sharmem.cpp (Text)" sed 's/^X//' << 'SHAR_EOF' > sharmem.cpp && X// sharmem.cpp A Shared Memory Object base class implementation X Xstatic const char rcsid[] = "@(#)sharmem.c++ 1.2 13:58:22 11/9/92 EFC"; X X#include <iostream.h> X X#include <sharmem.hpp> X Xextern int errno; X Xvoid* Shared::operator new(size_t blocksize) X{ X Shared *rtn; X int shmsize, shmid; X X X shmsize = blocksize; X shmid = shmget( IPC_PRIVATE, shmsize, (IPC_CREAT | 0600) ); X if ( shmid == -1 ) X { X cerr << "Shared::new() shared memory get (shmget) failed (" << X errno << ")\n", X exit(1); X } X X X X if ( (int)(rtn = (Shared *)shmat( shmid, 0, SHM_RND) ) == -1 ) X { X cerr << "Shared::new() (1) shared memory attach (shmat) error (" << X errno << ")\n"; X exit(1); X } X X rtn->shmid = shmid; X rtn->ref_count = 1; X X return rtn; X X} X Xvoid* Shared::operator new(size_t, int master_is) X{ X Shared *rtn; X X if ( (int)(rtn = (Shared *)shmat( master_is, 0, SHM_RND) ) == -1 ) X { X cerr << "Shared::new() (2) shared memory attach (shmat) error (" << X errno << ")\n"; X exit(1); X } X X rtn->ref_count++; X X return rtn; X X} X Xvoid Shared::operator delete(void *p) X{ X Shared* ps = (Shared *)p; X X if ( ps->ref_count-- == 1 ) X shmctl( ps->shmid, IPC_RMID, NULL); X else X shmdt( p ); X} X X X SHAR_EOF chmod 0644 sharmem.cpp || echo "restore of sharmem.cpp fails" echo "x - extracting sharmem.hpp (Text)" sed 's/^X//' << 'SHAR_EOF' > sharmem.hpp && X// sharmem.hpp A Shared Memory Object base class definition X X// To use this class, an otherwise ordinary object can publicly inherit from X// this class, one process, the "master", can treat the object in a normal way X// all the other processes, the "clients", must declare the object as a pointer X// and instantiate the object with the special version of new that requires the X// shared memory block ID as a parameter X X X// rcsid: @(#)sharmem.hpp 1.2 13:58:10 11/9/92 EFC X X#ifndef _SHAR_MEM_HPP_ X#define _SHAR_MEM_HPP_ 1.2 X X#include <stdlib.h> X X#include <sys/types.h> X#include <sys/ipc.h> X#include <sys/shm.h> X Xclass Shared X{ X private: X int shmid, ref_count; X protected: X Shared() : id(shmid), ref_count(0) {} X public: X const int& id; // shared memory block id X void *operator new(size_t blocksize); // used by the master X void *operator new(size_t,int master_is); // used by clients X void operator delete(void *); X}; X X#endif SHAR_EOF chmod 0444 sharmem.hpp || echo "restore of sharmem.hpp fails" echo "x - extracting persist.cpp (Text)" sed 's/^X//' << 'SHAR_EOF' > persist.cpp && X// persist.cpp Test using shared memory objects as persistant objects X X// usage persist c create the objects X// persist r read (and remove) objects X X#define PROGRAM "persist" X X#include <fstream.h> X#include <stdlib.h> X#include <sysent.h> // for fork(), may be elsewhere on other machines X X#include "sharmem.hpp" X X Xextern int errno; X Xclass Cube : public Shared X{ X private: X int x, y, z; X public: X Cube() {} X Cube(int a, int b, int c) : x(a), y(b), z(c) {} X ~Cube() {} X void size(int a, int b, int c) { x = a; y = b; z = c; } X int volume() { return x * y * z; } X}; X X Xvoid main(int argc, char **argv) X{ X int shmid, cubeid; X Cube *cube; X Cube *image; X X if ( argc < 2 ) X { X cerr << "Usage:\n\t" << PROGRAM << " c\t\tto create new objects\n"; X cerr << '\t' << PROGRAM << " r\t\tto read and remove objects\n"; X exit(1); X } X X if ( *argv[1] == 'c' ) X { X X image = new Cube; X cube = new Cube; X X shmid = image->id; // need this so that the shared one corresponds X cubeid = cube->id; X X X ofstream fout( "keys.dat" ); X if ( !fout ) X { X cerr << PROGRAM << " unable to open 'keys.dat' for output\n"; X exit(1); X } X X X fout << shmid << '\n' << cubeid << '\n'; X X fout.close(); X X image->size(2,3,4); X X cube->size(5,6,7); X } X else if ( *argv[1] == 'r' ) X { X X ifstream fin( "keys.dat" ); X if ( !fin ) X { X cerr << PROGRAM << " unable to open 'keys.dat' for input\n"; X exit(1); X } X X fin >> shmid >> cubeid; X X X fin.close(); X X cerr << "shmid: " << shmid << "\tcubeid: " << cubeid << endl; X X image = new(shmid) Cube; X cube = new(cubeid) Cube; X X } X else X { X X cerr << "Usage:\n\t" << PROGRAM << "c\t\tto create new objects\n"; X cerr << '\t' << PROGRAM << "r\t\tto read and remove objects\n"; X exit(1); X X } X X X X cout << "The cube volume is: " << image->volume() << endl; X X cout << "The 2nd cube volume is: " << cube->volume() << endl; X X X // NOTE: If you don't do this, you will eventually consume ALL X // the systems shared memory resources X X if ( *argv[1] == 'r' ) X { X delete image; X delete cube; X } X X} X X X X X SHAR_EOF chmod 0666 persist.cpp || echo "restore of persist.cpp fails" echo "x - extracting smem.cpp (Text)" sed 's/^X//' << 'SHAR_EOF' > smem.cpp && X// smem.cpp Test using shared memory objects (and optionally semaphores) X// the synchronization WITHOUT semaphores will only work for simple X// programs (like this one), using SEMAPHORES is the preferred way X// to go. X X#define PROGRAM "smem" X X#include <iostream.h> X#include <stdlib.h> X#include <sysent.h> // for fork() X X#include "sharmem.hpp" X X// #define USE_SEMAPHORES X X#ifdef USE_SEMAPHORES X#include "semaphore.hpp" X X#define NSEM 1 /* set to the number of semaphores to use */ X X#define SEM1 0 X#define SEM2 (NSEM-1) X X#endif X Xclass Cube : public Shared X{ X private: X int x, y, z; X public: X Cube() {} X Cube(int a, int b, int c) : x(a), y(b), z(c) {} X ~Cube() {} X void size(int a, int b, int c) { x = a; y = b; z = c; } X int volume() { return x * y * z; } X}; X X XCube *image; X Xint semid = 1234; X Xvoid main() X{ X int child; X int shmid, cubeid; X Cube *cube; X X image = new Cube; X cube = new Cube; X X shmid = image->id; // need this so that the shared one corresponds X cubeid = cube->id; X X#ifdef USE_SEMAPHORES X semaphore sem(semid, NSEM, 0); X#endif X X if ( fork() == 0 ) X { X delete image; // get rid of childs copy X X image = new(shmid) Cube; // attach to shared copy of image X X#ifdef USE_SEMAPHORES X semaphore sem(semid, NSEM, 0); X#endif X X child = getpid(); X cout << "I am the child process: " << child; X image->size(2,3,4); X cout << "\tThe cube volume is: " << image->volume() << endl; X X delete image; X X sleep(1); X#ifdef USE_SEMAPHORES X cerr << "(C1) Semaphore values: " << sem.value(SEM1) << '\n'; X sem[SEM1]++; X cerr << "(C1) Semaphore values: " << sem.value(SEM1) << '\n'; X#endif X exit( 0 ); X } X X if ( fork() == 0 ) X { X X delete image; // get rid of childs copy X X image = new(cubeid) Cube; // attach to shared copy of cube X#ifdef USE_SEMAPHORES X semaphore sem(semid,NSEM,0); X#endif X X child = getpid(); X cout << "I am the child process: " << child; X image->size(5,6,7); X cout << "\tThe cube volume is: " << image->volume() << endl; X X X delete image; X X#ifdef USE_SEMAPHORES X cerr << "(C2) Semaphore values: " << sem.value(SEM2) << '\n'; X sem[SEM2]++; X cerr << "(C2) Semaphore values: " << sem.value(SEM2) << '\n'; X#endif X exit( 0 ); X } X X // parent does this X X // sleep( 3 ); X X#ifdef USE_SEMAPHORES X cerr << "(P) Semaphore values: " << sem.value(0) << '\n'; X cerr << "Decrementing the semaphore the first time\n"; X sem[SEM1]--; X cerr << "Decrementing the semaphore the second time\n"; X sem[SEM2]--; X#else X int status; X child = wait(&status); X child = wait(&status); X cout << "The last child was: " << child << endl; X#endif X X cout << "The cube volume is: " << image->volume() << endl; X X cout << "The 2nd cube volume is: " << cube->volume() << endl; X X X // NOTE: If you don't do this, you will eventually consume ALL X // the systems shared memory resources X X delete image; X delete cube; X X} X X X X X SHAR_EOF chmod 0666 smem.cpp || echo "restore of smem.cpp fails" echo "x - extracting smema.cpp (Text)" sed 's/^X//' << 'SHAR_EOF' > smema.cpp && X// smema.cpp Test using shared memory objects (and optionally semaphores) X// two independent programs are used, this one creates the space and X// writes the keys to a file, the second one reads the keys and access the X// data X X#define PROGRAM "smemA" X X#include <fstream.h> X#include <stdlib.h> X#include <sysent.h> // for fork() X X#include "sharmem.hpp" X X// #define USE_SEMAPHORES X X#ifdef USE_SEMAPHORES X#include "semaphore.hpp" X X#define NSEM 1 /* set to the number of semaphores to use */ X X#define SEM1 0 X#define SEM2 (NSEM-1) X X#endif X X Xclass Cube : public Shared X{ X private: X int x, y, z; X public: X Cube() {} X Cube(int a, int b, int c) : x(a), y(b), z(c) {} X ~Cube() {} X void size(int a, int b, int c) { x = a; y = b; z = c; } X int volume() { return x * y * z; } X}; X X Xint semid = 1234; X Xvoid main() X{ X int shmid, cubeid; X Cube *cube; X Cube *image; X X X image = new Cube; X cube = new Cube; X X shmid = image->id; // need this so that the shared one corresponds X cubeid = cube->id; X X#ifdef USE_SEMAPHORES X semaphore sem(semid, NSEM, 0); X#endif X X ofstream fout( "keys.dat" ); X if ( !fout ) X { X cerr << PROGRAM << " unable to open 'keys.dat' for output\n"; X exit(1); X } X X X fout << shmid << '\n' << cubeid << '\n' << semid << '\n'; X X fout.close(); X X X // sleep( 3 ); X X#ifdef USE_SEMAPHORES X for (int i = 0; i < NSEM; i++) X cerr << "(P) Semaphore values: " << sem.value(i) << '\n'; X cerr << "Decrementing the semaphore the first time\n"; X sem[SEM1]--; X for (i = 0; i < NSEM; i++) X cerr << "(P) Semaphore values: " << sem.value(i) << '\n'; X cerr << "Decrementing the semaphore the second time\n"; X sem[SEM2]--; X for (i = 0; i < NSEM; i++) X cerr << "(P) Semaphore values: " << sem.value(i) << '\n'; X#else X // no semaphores so, X sleep( 5 ); // just wait a while and hope the obect is ready X X#endif X X cout << "A: The cube volume is: " << image->volume() << endl; X X cout << "A: The 2nd cube volume is: " << cube->volume() << endl; X X X // NOTE: If you don't do this, you will eventually consume ALL X // the systems shared memory resources X X delete image; X delete cube; X X} X X X X X SHAR_EOF chmod 0666 smema.cpp || echo "restore of smema.cpp fails" echo "x - extracting smemb.cpp (Text)" sed 's/^X//' << 'SHAR_EOF' > smemb.cpp && X// smemb.cpp Test using shared memory objects (and optionally semaphores) X// two independent programs are used, this one X// reads the keys and access the data X X#define PROGRAM "smemB" X X X#include <fstream.h> X#include <stdlib.h> X#include <sysent.h> // for fork() X X#include "sharmem.hpp" X X// #define USE_SEMAPHORES X X#ifdef USE_SEMAPHORES X#include "semaphore.hpp" X X#define NSEM 1 /* set to the number of semaphores to use */ X X#define SEM1 0 X#define SEM2 (NSEM-1) X X#endif X Xclass Cube : public Shared X{ X private: X int x, y, z; X public: X Cube() {} X Cube(int a, int b, int c) : x(a), y(b), z(c) {} X ~Cube() {} X void size(int a, int b, int c) { x = a; y = b; z = c; } X int volume() { return x * y * z; } X}; X X XCube *image; X X Xvoid main() X{ X int child; X int shmid, cubeid, semid; X Cube *cube; X X ifstream fin( "keys.dat" ); X if ( !fin ) X { X cerr << PROGRAM << " unable to open 'keys.dat' for input\n"; X exit(1); X } X X fin >> shmid >> cubeid >> semid; X X X fin.close(); X X cerr << "shmid: " << shmid << "\tcubeid: " << cubeid X << "\tsemid: " << semid << endl; X X image = new(shmid) Cube; X cube = new(cubeid) Cube; X X X#ifdef USE_SEMAPHORES X semaphore sem(semid, NSEM, 0); X#endif X X X child = getpid(); X cout << "I am the child process: " << child; X image->size(2,3,4); X cout << "\tThe cube volume is: " << image->volume() << endl; X X delete image; X X sleep(1); X#ifdef USE_SEMAPHORES X cerr << "(C1) Semaphore values: " << sem.value(SEM1) << '\n'; X sem[SEM1]++; X cerr << "(C1) Semaphore values: " << sem.value(SEM1) << '\n'; X#endif X X X child = getpid(); X cout << "B: I am the second process: " << child; X cube->size(5,6,7); X cout << "\tThe cube volume is: " << cube->volume() << endl; X X X delete cube; X X#ifdef USE_SEMAPHORES X cerr << "(C2) Semaphore values: " << sem.value(SEM2) << '\n'; X sem[SEM2]++; X cerr << "(C2) Semaphore values: " << sem.value(SEM2) << '\n'; X#endif X X X X} X X X X X SHAR_EOF chmod 0666 smemb.cpp || echo "restore of smemb.cpp fails" exit 0 -- Everett (Skip) Carter Phone: 408-656-3318 FAX: 408-656-2712 Naval Postgraduate School INTERNET: skip@taygeta.oc.nps.navy.mil Dept. of Oceanography, Code OC/CR UUCP: ...!uunet!taygeta!skip Monterey, CA. 93943 TELEMAIL: s.carter/omnet (please note the new phone numbers) -- Everett (Skip) Carter Phone: 408-656-3318 FAX: 408-656-2712 Naval Postgraduate School INTERNET: skip@taygeta.oc.nps.navy.mil Dept. of Oceanography, Code OC/CR UUCP: ...!uunet!taygeta!skip Monterey, CA. 93943 TELEMAIL: s.carter/omnet (please note the new phone numbers)