F. Source code for the GLib D-Bus asynchronous examples
- F.1 glib-dbus-async/common-defs.h
- F.2 glib-dbus-async/value-dbus-interface.xml
- F.3 glib-dbus-async/server.c
- F.4 glib-dbus-async/client-stubs.c
- F.5 glib-dbus-async/client-glib.c
- F.6 glib-dbus-async/Makefile
F. Source code for the GLib D-Bus asynchronous examples
F.1 glib-dbus-async/common-defs.h
glib-dbus-async/common-defs.h#ifndef INCLUDE_COMMON_DEFS_H #define INCLUDE_COMMON_DEFS_H /** * This maemo code example is licensed under a MIT-style license, * that can be found in the file called "License" in the same * directory as this file. * Copyright (c) 2007-2008 Nokia Corporation. All rights reserved. * * This file includes the common symbolic defines for both client and * the server. Normally this kind of information would be part of the * object usage documentation, but in this example we take the easy * way out. * * To re-iterate: You could just as easily use strings in both client * and server, and that would be the more common way. */ /* Well-known name for this service. */ #define VALUE_SERVICE_NAME "org.maemo.Platdev_ex" /* Object path to the provided object. */ #define VALUE_SERVICE_OBJECT_PATH "/GlobalValue" /* And we're interested in using it through this interface. This must match the entry in the interface definition XML. */ #define VALUE_SERVICE_INTERFACE "org.maemo.Value" /* Symbolic constants for the signal names to use with GLib. These need to map into the D-Bus signal names. */ #define SIGNAL_CHANGED_VALUE1 "changed_value1" #define SIGNAL_CHANGED_VALUE2 "changed_value2" #define SIGNAL_OUTOFRANGE_VALUE1 "outofrange_value1" #define SIGNAL_OUTOFRANGE_VALUE2 "outofrange_value2" #endif
F.2 glib-dbus-async/value-dbus-interface.xml
glib-dbus-async/value-dbus-interface.xml<?xml version="1.0" encoding="UTF-8" ?> <!- This maemo code example is licensed under a MIT-style license, that can be found in the file called "License" in the same directory as this file. Copyright (c) 2007-2008 Nokia Corporation. All rights reserved. -> <!- If you keep the following DOCTYPE tag in your interface specification, xmllint can fetch the DTD over the Internet for validation automatically. -> <!DOCTYPE node PUBLIC "-//freedesktop//DTD D-Bus Object Introspection 1.0//EN" "http://standards.freedesktop.org/dbus/1.0/introspect.dtd"> <!- This file defines the D-Bus interface for a simple object, that will hold a simple state consisting of two values (one a 32-bit integer, the other a double). The object will always generate a signal when a value is changed (changed_value1 or changed_value2). It has also a min and max thresholds: when a client tries to set the value too high or too low, the object will generate a signal (outofrange_value1 or outofrange_value2). The thresholds are not modifiable (nor viewable) via this interface. They are specified in integers and apply to both internal values. Adding per-value thresholds would be a good idea. Generalizing the whole interface to support multiple concurrent values would be another good idea. The interface name is "org.maemo.Value". One known reference implementation is provided for it by the "/GlobalValue" object found via a well-known name of "org.maemo.Platdev_ex". -> <node> <interface name="org.maemo.Value"> <!- Method definitions -> <!- getvalue1(): returns the first value (int) -> <method name="getvalue1"> <!- NOTE Naming arguments is not mandatory, but is recommended so that D-Bus introspection tools are more useful. Otherwise the arguments will be automatically named "arg0", "arg1" and so on. -> <arg type="i" name="cur_value" direction="out"/> </method> <!- getvalue2(): returns the second value (double) -> <method name="getvalue2"> <arg type="d" name="cur_value" direction="out"/> </method> <!- setvalue1(int newValue): sets value1 -> <method name="setvalue1"> <arg type="i" name="new_value" direction="in"/> </method> <!- setvalue2(double newValue): sets value2 -> <method name="setvalue2"> <arg type="d" name="new_value" direction="in"/> </method> <!- Signal (D-Bus) definitions -> <!- NOTE: The current version of dbus-bindings-tool doesn't actually enforce the signal arguments _at_all_. Signals need to be declared in order to be passed through the bus itself, but otherwise no checks are done! For example, you could leave the signal arguments unspecified completely, and the code would still work. -> <!- Signals to tell interested clients about state change. We send a string parameter with them. They never can have arguments with direction=in. -> <signal name="changed_value1"> <arg type="s" name="change_source_name" direction="out"/> </signal> <signal name="changed_value2"> <arg type="s" name="change_source_name" direction="out"/> </signal> <!- Signals to tell interested clients that values are outside the internally configured range (thresholds). -> <signal name="outofrange_value1"> <arg type="s" name="outofrange_source_name" direction="out"/> </signal> <signal name="outofrange_value2"> <arg type="s" name="outofrange_source_name" direction="out"/> </signal> </interface> </node>
F.3 glib-dbus-async/server.c
glib-dbus-async/server.c/** * Same server as in glib-dbus-signals, but with a 5 second sleep * between each client operation (in order to demonstrate the benefits * of using the async interface at the client end). * * This maemo code example is licensed under a MIT-style license, * that can be found in the file called "License" in the same * directory as this file. * Copyright (c) 2007-2008 Nokia Corporation. All rights reserved. */ #include <glib.h> #include <dbus/dbus-glib.h> #include <stdlib.h> /* exit, EXIT_FAILURE */ #include <unistd.h> /* daemon */ /* How many microseconds to delay between each client operation. */ #define SERVER_DELAY_USEC (5*1000000UL) /* Pull symbolic constants that are shared (in this example) between the client and the server. */ #include "common-defs.h" /** * Define enumerations for the different signals that we can generate * (so that we can refer to them within the signals-array [below] * using symbolic names). These are not the same as the signal name * strings. * * NOTE: E_SIGNAL_COUNT is NOT a signal enum. We use it as a * convenient constant giving the number of signals defined so * far. It needs to be listed last. */ typedef enum { E_SIGNAL_CHANGED_VALUE1, E_SIGNAL_CHANGED_VALUE2, E_SIGNAL_OUTOFRANGE_VALUE1, E_SIGNAL_OUTOFRANGE_VALUE2, E_SIGNAL_COUNT } ValueSignalNumber; typedef struct { /* The parent class object state. */ GObject parent; /* Our first per-object state variable. */ gint value1; /* Our second per-object state variable. */ gdouble value2; } ValueObject; typedef struct { /* The parent class state. */ GObjectClass parent; /* The minimum number under which values will cause signals to be emitted. */ gint thresholdMin; /* The maximum number over which values will cause signals to be emitted. */ gint thresholdMax; /* Signals created for this class. */ guint signals[E_SIGNAL_COUNT]; } ValueObjectClass; /* Forward declaration of the function that will return the GType of the Value implementation. Not used in this program. */ GType value_object_get_type(void); /* Macro for the above. It is common to define macros using the naming convention (seen below) for all GType implementations, and that's why we're going to do that here as well. */ #define VALUE_TYPE_OBJECT (value_object_get_type()) #define VALUE_OBJECT(object) \ (G_TYPE_CHECK_INSTANCE_CAST ((object), \ VALUE_TYPE_OBJECT, ValueObject)) #define VALUE_OBJECT_CLASS(klass) \ (G_TYPE_CHECK_CLASS_CAST ((klass), \ VALUE_TYPE_OBJECT, ValueObjectClass)) #define VALUE_IS_OBJECT(object) \ (G_TYPE_CHECK_INSTANCE_TYPE ((object), \ VALUE_TYPE_OBJECT)) #define VALUE_IS_OBJECT_CLASS(klass) \ (G_TYPE_CHECK_CLASS_TYPE ((klass), \ VALUE_TYPE_OBJECT)) #define VALUE_OBJECT_GET_CLASS(obj) \ (G_TYPE_INSTANCE_GET_CLASS ((obj), \ VALUE_TYPE_OBJECT, ValueObjectClass)) G_DEFINE_TYPE(ValueObject, value_object, G_TYPE_OBJECT) /** * Since the stub generator will reference the functions from a call * table, the functions must be declared before the stub is included. */ gboolean value_object_getvalue1(ValueObject* obj, gint* value_out, GError** error); gboolean value_object_getvalue2(ValueObject* obj, gdouble* value_out, GError** error); gboolean value_object_setvalue1(ValueObject* obj, gint value_in, GError** error); gboolean value_object_setvalue2(ValueObject* obj, gdouble value_in, GError** error); /** * Pull in the stub for the server side. */ #include "value-server-stub.h" /* A small macro that will wrap g_print and expand to empty when server will daemonize. We use this to add debugging info on the server side, but if server will be daemonized, it doesn't make sense to even compile the code in. The macro is quite "hairy", but very convenient. */ #ifdef NO_DAEMON #define dbg(fmtstr, args...) \ (g_print(PROGNAME ":%s: " fmtstr "\n", __func__, ##args)) #else #define dbg(dummy...) #endif /** * Per object initializer * * Only sets up internal state (both values set to zero) */ static void value_object_init(ValueObject* obj) { dbg("Called"); g_assert(obj != NULL); obj->value1 = 0; obj->value2 = 0.0; } /** * Per class initializer * * Sets up the thresholds (-100 .. 100), creates the signals that we * can emit from any object of this class and finally registers the * type into the GLib/D-Bus wrapper so that it may add its own magic. */ static void value_object_class_init(ValueObjectClass* klass) { /* Since all signals have the same prototype (each will get one string as a parameter), we create them in a loop below. The only difference between them is the index into the klass->signals array, and the signal name. Since the index goes from 0 to E_SIGNAL_COUNT-1, we just specify the signal names into an array and iterate over it. Note that the order here must correspond to the order of the enumerations before. */ const gchar* signalNames[E_SIGNAL_COUNT] = { SIGNAL_CHANGED_VALUE1, SIGNAL_CHANGED_VALUE2, SIGNAL_OUTOFRANGE_VALUE1, SIGNAL_OUTOFRANGE_VALUE2 }; /* Loop variable */ int i; dbg("Called"); g_assert(klass != NULL); /* Setup sane minimums and maximums for the thresholds. There is no way to change these afterwards (currently), so you can consider them as constants. */ klass->thresholdMin = -100; klass->thresholdMax = 100; dbg("Creating signals"); /* Create the signals in one loop, since they all are similar (except for the names). */ for (i = 0; i < E_SIGNAL_COUNT; i++) { guint signalId; /* Most of the time you will encounter the following code without comments. This is why all the parameters are documented directly below. */ signalId = /* str name of the signal */ g_signal_new(signalNames[i], /* GType to which signal is bound to */ G_OBJECT_CLASS_TYPE(klass), /* Combination of GSignalFlags which tell the signal dispatch machinery how and when to dispatch this signal. The most common is the G_SIGNAL_RUN_LAST specification. */ G_SIGNAL_RUN_LAST, /* Offset into the class structure for the type function pointer. Since we're implementing a simple class/type, we'll leave this at zero. */ 0, /* GSignalAccumulator to use. We don't need one. */ NULL, /* User-data to pass to the accumulator. */ NULL, /* Function to use to marshal the signal data into the parameters of the signal call. Luckily for us, GLib (GCClosure) already defines just the function that we want for a signal handler that we don't expect any return values (void) and one that will accept one string as parameter (besides the instance pointer and pointer to user-data). If no such function would exist, you would need to create a new one (by using glib-genmarshal tool). */ g_cclosure_marshal_VOID__STRING, /* Return GType of the return value. The handler does not return anything, so we use G_TYPE_NONE to mark that. */ G_TYPE_NONE, /* Number of parameter GTypes to follow. */ 1, /* GType(s) of the parameters. We only have one. */ G_TYPE_STRING); /* Store the signal Id into the class state, so that we can use it later. */ klass->signals[i] = signalId; /* Proceed with the next signal creation. */ } /* All signals created. */ dbg("Binding to GLib/D-Bus"); /* Time to bind this GType into the GLib/D-Bus wrappers. NOTE: This is not yet "publishing" the object on the D-Bus, but since it is only allowed to do this once per class creation, the safest place to put it is in the class initializer. Specifically, this function adds "method introspection data" to the class so that methods can be called over the D-Bus. */ dbus_g_object_type_install_info(VALUE_TYPE_OBJECT, &dbus_glib_value_object_object_info); dbg("Done"); /* All done. Class is ready to be used for instantiating objects */ } /** * Utility helper to emit a signal given with internal enumeration and * the passed string as the signal data. * * Used in the setter functions below. */ static void value_object_emitSignal(ValueObject* obj, ValueSignalNumber num, const gchar* message) { /* In order to access the signal identifiers, we need to get a hold of the class structure first. */ ValueObjectClass* klass = VALUE_OBJECT_GET_CLASS(obj); /* Check that the given num is valid (abort if not). Given that this file is the module actually using this utility, you can consider this check superfluous (but useful for development work). */ g_assert((num < E_SIGNAL_COUNT) && (num >= 0)); dbg("Emitting signal id %d, with message '%s'", num, message); /* This is the simplest way of emitting signals. */ g_signal_emit(/* Instance of the object that is generating this signal. This will be passed as the first parameter to the signal handler (eventually). But obviously when speaking about D-Bus, a signal caught on the other side of D-Bus will be first processed by the GLib-wrappers (the object proxy) and only then processed by the signal handler. */ obj, /* Signal id for the signal to generate. These are stored inside the class state structure. */ klass->signals[num], /* Detail of signal. Since we are not using detailed signals, we leave this at zero (default). */ 0, /* Data to marshal into the signal. In our case it's just one string. */ message); /* g_signal_emit returns void, so we cannot check for success. */ /* Done emitting signal. */ } /** * Utility to check the given integer against the thresholds. * Will return TRUE if thresholds are not exceeded, FALSE otherwise. * * Used in the setter functions below. */ static gboolean value_object_thresholdsOk(ValueObject* obj, gint value) { /* Thresholds are in class state data, get access to it */ ValueObjectClass* klass = VALUE_OBJECT_GET_CLASS(obj); return ((value >= klass->thresholdMin) && (value <= klass->thresholdMax)); } /** * Function that gets called when someone tries to execute "setvalue1" * over the D-Bus. (Actually the marshaling code from the stubs gets * executed first, but they will eventually execute this function.) * * NOTE: If you change the name of this function, the generated * stubs will no longer find it! On the other hand, if you * decide to modify the interface XML, this is one of the places * that you'll have to modify as well. * This applies to the next four functions (including this one). */ gboolean value_object_setvalue1(ValueObject* obj, gint valueIn, GError** error) { dbg("Called (valueIn=%d)", valueIn); g_assert(obj != NULL); dbg("Delaying operation"); g_usleep(SERVER_DELAY_USEC); /* Compare the current value against old one. If they're the same, we don't need to do anything (except return success). */ if (obj->value1 != valueIn) { /* Change the value. */ obj->value1 = valueIn; /* Emit the "changed_value1" signal. */ value_object_emitSignal(obj, E_SIGNAL_CHANGED_VALUE1, "value1"); /* If new value falls outside the thresholds, emit "outofrange_value1" signal as well. */ if (!value_object_thresholdsOk(obj, valueIn)) { value_object_emitSignal(obj, E_SIGNAL_OUTOFRANGE_VALUE1, "value1"); } } /* Return success to GLib/D-Bus wrappers. In this case we don't need to touch the supplied error pointer-pointer. */ return TRUE; } /** * Function that gets executed on "setvalue2". * Other than this function operating with different type input * parameter (and different internal value), all the comments from * set_value1 apply here as well. */ gboolean value_object_setvalue2(ValueObject* obj, gdouble valueIn, GError** error) { dbg("Called (valueIn=%.3f)", valueIn); g_assert(obj != NULL); dbg("Delaying operation"); g_usleep(SERVER_DELAY_USEC); /* Normally comparing doubles against other doubles is a bad idea, since multiple values can "collide" into one binary representation. In our case, it is not a real problem, as we're not interested in numeric comparison, but testing whether the binary content is about to change. Also, as the value has been sent by client over the D-Bus, it has already been reduced. */ if (obj->value2 != valueIn) { obj->value2 = valueIn; value_object_emitSignal(obj, E_SIGNAL_CHANGED_VALUE2, "value2"); if (!value_object_thresholdsOk(obj, valueIn)) { value_object_emitSignal(obj, E_SIGNAL_OUTOFRANGE_VALUE2, "value2"); } } return TRUE; } /** * Function that gets executed on "getvalue1". * We don't signal the get operations, so this will be simple. */ gboolean value_object_getvalue1(ValueObject* obj, gint* valueOut, GError** error) { dbg("Called (internal value1 is %d)", obj->value1); g_assert(obj != NULL); dbg("Delaying operation"); g_usleep(SERVER_DELAY_USEC); /* Check that the target pointer is not NULL. Even is the only caller for this will be the GLib-wrapper code, we cannot trust the stub generated code and should handle the situation. We will terminate with an error in this case. Another option would be to create a new GError, and store the error condition there. */ g_assert(valueOut != NULL); /* Copy the current first value to caller specified memory. */ *valueOut = obj->value1; /* Return success. */ return TRUE; } /** * Function that gets executed on "getvalue2". * (Again, similar to "getvalue1"). */ gboolean value_object_getvalue2(ValueObject* obj, gdouble* valueOut, GError** error) { dbg("Called (internal value2 is %.3f)", obj->value2); g_assert(obj != NULL); dbg("Delaying operation"); g_usleep(SERVER_DELAY_USEC); g_assert(valueOut != NULL); *valueOut = obj->value2; return TRUE; } /** * Print out an error message and optionally quit (if fatal is TRUE) */ static void handleError(const char* msg, const char* reason, gboolean fatal) { g_printerr(PROGNAME ": ERROR: %s (%s)\n", msg, reason); if (fatal) { exit(EXIT_FAILURE); } } /** * The main server code * * 1) Init GType/GObject * 2) Create a mainloop * 3) Connect to the Session bus * 4) Get a proxy object representing the bus itself * 5) Register the well-known name by which clients can find us. * 6) Create one Value object that will handle all client requests. * 7) Register it on the bus (will be found via "/GlobalValue" object * path) * 8) Daemonize the process (if not built with NO_DAEMON) * 9) Start processing requests (run GMainLoop) * * This program will not exit (unless it encounters critical errors). */ int main(int argc, char** argv) { /* The GObject representing a D-Bus connection. */ DBusGConnection* bus = NULL; /* Proxy object representing the D-Bus service object. */ DBusGProxy* busProxy = NULL; /* Will hold one instance of ValueObject that will serve all the requsts. */ ValueObject* valueObj = NULL; /* GMainLoop for our program. */ GMainLoop* mainloop = NULL; /* Will store the result of the RequestName RPC here. */ guint result; GError* error = NULL; /* Initialize the GType/GObject system. */ g_type_init(); /* Create a main loop that will dispatch callbacks. */ mainloop = g_main_loop_new(NULL, FALSE); if (mainloop == NULL) { /* Print error and terminate. */ handleError("Couldn't create GMainLoop", "Unknown(OOM?)", TRUE); } g_print(PROGNAME ":main Connecting to the Session D-Bus.\n"); bus = dbus_g_bus_get(DBUS_BUS_SESSION, &error); if (error != NULL) { /* Print error and terminate. */ handleError("Couldn't connect to session bus", error->message, TRUE); } g_print(PROGNAME ":main Registering the well-known name (%s)\n", VALUE_SERVICE_NAME); /* In order to register a well-known name, we need to use the "RequestMethod" of the /org/freedesktop/DBus interface. Each bus provides an object that will implement this interface. In order to do the call, we need a proxy object first. DBUS_SERVICE_DBUS = "org.freedesktop.DBus" DBUS_PATH_DBUS = "/org/freedesktop/DBus" DBUS_INTERFACE_DBUS = "org.freedesktop.DBus" */ busProxy = dbus_g_proxy_new_for_name(bus, DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS); if (busProxy == NULL) { handleError("Failed to get a proxy for D-Bus", "Unknown(dbus_g_proxy_new_for_name)", TRUE); } /* Attempt to register the well-known name. The RPC call requires two parameters: - arg0: (D-Bus STRING): name to request - arg1: (D-Bus UINT32): flags for registration. (please see "org.freedesktop.DBus.RequestName" in http://dbus.freedesktop.org/doc/dbus-specification.html) Will return one uint32 giving the result of the RPC call. We're interested in 1 (we're now the primary owner of the name) or 4 (we were already the owner of the name, however in this application it wouldn't make much sense). The function will return FALSE if it sets the GError. */ if (!dbus_g_proxy_call(busProxy, /* Method name to call. */ "RequestName", /* Where to store the GError. */ &error, /* Parameter type of argument 0. Note that since we're dealing with GLib/D-Bus wrappers, you will need to find a suitable GType instead of using the "native" D-Bus type codes. */ G_TYPE_STRING, /* Data of argument 0. In our case, this is the well-known name for our server example ("org.maemo.Platdev_ex"). */ VALUE_SERVICE_NAME, /* Parameter type of argument 1. */ G_TYPE_UINT, /* Data of argument 0. This is the "flags" argument of the "RequestName" method which can be use to specify what the bus service should do when the name already exists on the bus. We'll go with defaults. */ 0, /* Input arguments are terminated with a special GType marker. */ G_TYPE_INVALID, /* Parameter type of return value 0. For "RequestName" it is UINT32 so we pick the GType that maps into UINT32 in the wrappers. */ G_TYPE_UINT, /* Data of return value 0. These will always be pointers to the locations where the proxy can copy the results. */ &result, /* Terminate list of return values. */ G_TYPE_INVALID)) { handleError("D-Bus.RequestName RPC failed", error->message, TRUE); /* Note that the whole call failed, not "just" the name registration (we deal with that below). This means that something bad probably has happened and there's not much we can do (hence program termination). */ } /* Check the result code of the registration RPC. */ g_print(PROGNAME ":main RequestName returned %d.\n", result); if (result != 1) { handleError("Failed to get the primary well-known name.", "RequestName result != 1", TRUE); /* In this case we could also continue instead of terminating. We could retry the RPC later. Or "lurk" on the bus waiting for someone to tell us what to do. If we would be publishing multiple services and/or interfaces, it even might make sense to continue with the rest anyway. In our simple program, we terminate. Not much left to do for this poor program if the clients won't be able to find the Value object using the well-known name. */ } g_print(PROGNAME ":main Creating one Value object.\n"); /* The NULL at the end means that we have stopped listing the property names and their values that would have been used to set the properties to initial values. Our simple Value implementation does not support GObject properties, and also doesn't inherit anything interesting from GObject directly, so there are no properties to set. For more examples on properties see the first GTK+ example programs from the Application Development material. NOTE: You need to keep at least one reference to the published object at all times, unless you want it to disappear from the D-Bus (implied by API reference for dbus_g_connection_register_g_object(). */ valueObj = g_object_new(VALUE_TYPE_OBJECT, NULL); if (valueObj == NULL) { handleError("Failed to create one Value instance.", "Unknown(OOM?)", TRUE); } g_print(PROGNAME ":main Registering it on the D-Bus.\n"); /* The function does not return any status, so can't check for errors here. */ dbus_g_connection_register_g_object(bus, VALUE_SERVICE_OBJECT_PATH, G_OBJECT(valueObj)); g_print(PROGNAME ":main Ready to serve requests (daemonizing).\n"); #ifndef NO_DAEMON /* This will attempt to daemonize this process. It will switch this process' working directory to / (chdir) and then reopen stdin, stdout and stderr to /dev/null. Which means that all printouts that would occur after this, will be lost. Obviously the daemonization will also detach the process from the controlling terminal as well. */ if (daemon(0, 0) != 0) { g_error(PROGNAME ": Failed to daemonize.\n"); } #else g_print(PROGNAME ": Not daemonizing (built with NO_DAEMON-build define)\n"); #endif /* Start service requests on the D-Bus forever. */ g_main_loop_run(mainloop); /* This program will not terminate unless there is a critical error which will cause abort() to be used. Hence it will never reach this point. */ /* If it does, return failure exit code just in case. */ return EXIT_FAILURE; }
F.4 glib-dbus-async/client-stubs.c
glib-dbus-async/client-stubs.c/** * An approach for issuing RPC method calls using the * dbus-binding-tool generated wrappers. * * This maemo code example is licensed under a MIT-style license, * that can be found in the file called "License" in the same * directory as this file. * Copyright (c) 2007-2008 Nokia Corporation. All rights reserved. * * In order to shorten the code, the code for handling signals has * been removed as well as code dealing with value2. * * This program also demonstrates the inherent complexity when moving * from sync to async calls (more problem scenarios to handle). As * such, it is NOT suitable to be copy-pasted! */ #include <glib.h> #include <dbus/dbus-glib.h> #include <stdlib.h> /* exit */ #include <sys/time.h> /* struct timeval and friends */ #include <time.h> /* gettimeofday */ /* Pull the common symbolic defines. */ #include "common-defs.h" /* Pull in the client stubs that were generated with dbus-binding-tool */ #include "value-client-stub.h" /** * Print out an error message and optionally quit (if fatal is TRUE) */ static void handleError(const char* msg, const char* reason, gboolean fatal) { g_printerr(PROGNAME ": ERROR: %s (%s)\n", msg, reason); if (fatal) { exit(EXIT_FAILURE); } } /** * Utility to return a pointer to a statically allocated buffer that * holds the text representation of seconds since this program was * started. Not safe to use in threaded programs! */ static const gchar* timestamp(void) { /* Holds the "seconds since starting" string. */ static gchar buffer[200] = {}; /* Holds the starting timestamp. 0 means that it has not been initialized. */ static guint64 startTimestamp = 0; /* Holds the current timestamp. */ guint64 curTimestamp = 0; /* Temp storage for the secs + microseconds time. */ struct timeval tv; /* Temp storage for the difference between start and now. */ guint64 delta; /* Get current time and convert into microseconds flat. */ gettimeofday(&tv, NULL); /* Convert into microseconds. */ curTimestamp = (guint64)tv.tv_usec + ((guint64)tv.tv_sec)*1000000ULL; /* Running for the first time? */ if (startTimestamp == 0) { /* Copy to prev so that we get 0 delta. */ startTimestamp = curTimestamp; } /* Calculate the delta (in microseconds). */ delta = curTimestamp - startTimestamp; /* Create the string giving offset from start in seconds. */ g_snprintf(buffer, sizeof(buffer), "%2u.%.2u", (guint)delta / 1000000, ((guint)delta % 1000000) / 10000); /* Return pointer to the buffer (will always return a pointer to the same location. */ return buffer; } /** * This function will be called when the async setvalue1 will either * complete, timeout or fail (our server however does not signal * errors, but the client D-Bus library might). When this example * program is left running for a while, you will see all three cases. * * The prototype must match the one generated by the dbus-binding-tool * (org_maemo_Value_setvalue1_reply). * * Since there is no return value from the RPC, the only useful * parameter that we get is the error object, which we'll check. * If error is NULL, that means no error. Otherwise the RPC call * failed and we should check what the cause was. */ static void setValue1Completed(DBusGProxy* proxy, GError *error, gpointer userData) { g_print(PROGNAME ":%s:setValue1Completed\n", timestamp()); if (error != NULL) { g_printerr(PROGNAME " ERROR: %s\n", error->message); /* We need to release the error object since the stub code does not do it automatically. */ g_error_free(error); } else { g_print(PROGNAME " SUCCESS\n"); } } /** * This function will be called repeatedly from within the mainloop * timer launch code. * * It will launch asynchronous RPC method to set value1 with ever * increasing argument. */ static gboolean timerCallback(DBusGProxy* remoteobj) { /* Local value that we'll start updating to the remote object. */ static gint localValue1 = -80; /* Start the RPC. This is done by calling the stub function that will take the new value and the callback function to call on reply getting back. The stub returns a DBusGProxyCall object, but we don't need it so we'll ignore the return value. The return value could be used to cancel a pending request (from client side) with dbus_g_proxy_cancel_call. We could also pass a pointer to user-data (last parameter), but we don't need one in this example. It would normally be used to "carry around" the application state. */ g_print(PROGNAME ":%s:timerCallback launching setvalue1\n", timestamp()); org_maemo_Value_setvalue1_async(remoteobj, localValue1, setValue1Completed, NULL); g_print(PROGNAME ":%s:timerCallback setvalue1 launched\n", timestamp()); /* Step the local value forward. */ localValue1 += 10; /* Repeat timer later. */ return TRUE; } /** * The test program itself. * * 1) Setup GType/GSignal * 2) Create GMainLoop object * 3) Connect to the Session D-Bus * 4) Create a proxy GObject for the remote Value object * 5) Start a timer that will launch timerCallback once per second. * 6) Run main-loop (forever) */ int main(int argc, char** argv) { DBusGConnection* bus; /* The proxy object. */ DBusGProxy* remoteValue; GMainLoop* mainloop; GError* error = NULL; g_type_init(); mainloop = g_main_loop_new(NULL, FALSE); /* Failure to create the main loop is fatal (for us). */ if (mainloop == NULL) { handleError("Failed to create the mainloop", "Unknown (OOM?)", TRUE); } g_print(PROGNAME ":main Connecting to Session D-Bus.\n"); bus = dbus_g_bus_get(DBUS_BUS_SESSION, &error); if (error != NULL) { handleError("Couldn't connect to the Session bus", error->message, TRUE); } g_print(PROGNAME ":main Creating a GLib proxy object for Value.\n"); remoteValue = dbus_g_proxy_new_for_name(bus, VALUE_SERVICE_NAME, /* name */ VALUE_SERVICE_OBJECT_PATH, /* obj path */ VALUE_SERVICE_INTERFACE /* interface */); if (remoteValue == NULL) { handleError("Couldn't create the proxy object", "Unknown(dbus_g_proxy_new_for_name)", TRUE); } g_print(PROGNAME ":%s:main Starting main loop (first timer in 1s).\n", timestamp()); g_timeout_add(1000, (GSourceFunc)timerCallback, remoteValue); /* Run the program. */ g_main_loop_run(mainloop); /* Since the main loop is not stopped (by this code), we shouldn't ever get here. The program might abort() for other reasons. */ /* If it does, return failure as exit code. */ return 1; }
F.5 glib-dbus-async/client-glib.c
glib-dbus-async/client-glib.c/** * Same example as client-stubs, but implementing the asynchronous * logic by using GLib/D-Bus wrapper functions directly. This version * of the asynchronous client does not require the generated stubs. * * This maemo code example is licensed under a MIT-style license, * that can be found in the file called "License" in the same * directory as this file. * Copyright (c) 2007-2008 Nokia Corporation. All rights reserved. */ #include <glib.h> #include <dbus/dbus-glib.h> #include <stdlib.h> /* exit */ /* Pull the common symbolic defines. */ #include "common-defs.h" /** * Print out an error message and optionally quit (if fatal is TRUE) */ static void handleError(const char* msg, const char* reason, gboolean fatal) { g_printerr(PROGNAME ": ERROR: %s (%s)\n", msg, reason); if (fatal) { exit(EXIT_FAILURE); } } /** * This function will be called when the async setvalue1 will either * complete, timeout or fail (same as before). The main difference in * using GLib/D-Bus wrappers is that we need to "collect" the return * value (or error). This is done with the _end_call function. * * Note that all callbacks that are to be registered for RPC async * notifications using dbus_g_proxy_begin_call must follow the * following prototype: DBusGProxyCallNotify . */ static void setValue1Completed(DBusGProxy* proxy, DBusGProxyCall* call, gpointer userData) { /* This will hold the GError object (if any). */ GError* error = NULL; g_print(PROGNAME ":setValue1Completed\n"); /* We next need to collect the results from the RPC call. The function returns FALSE on errors (which we check), although we could also check whether error-ptr is still NULL. */ if (!dbus_g_proxy_end_call(proxy, /* The call that we're collecting. */ call, /* Where to store the error (if any). */ &error, /* Next we list the GType codes for all the arguments we expect back. In our case there are none, so set to invalid. */ G_TYPE_INVALID)) { /* Some error occurred while collecting the result. */ g_printerr(PROGNAME " ERROR: %s\n", error->message); g_error_free(error); } else { g_print(PROGNAME " SUCCESS\n"); } } /** * This function will be called repeatedly from within the mainloop * timer launch code. * * It will launch asynchronous RPC method to set value1 with ever * increasing argument. */ static gboolean timerCallback(DBusGProxy* remoteobj) { /* Local value that we'll start updating to the remote object. */ static gint localValue1 = -80; /* Start the first RPC. The call using GLib/D-Bus is only slightly more complex than the stubs. The overall operation is the same. */ g_print(PROGNAME ":timerCallback launching setvalue1\n"); dbus_g_proxy_begin_call(remoteobj, /* Method name. */ "setvalue1", /* Callback to call on "completion". */ setValue1Completed, /* User-data to pass to callback. */ NULL, /* Function to call to free userData after callback returns. */ NULL, /* First argument GType. */ G_TYPE_INT, /* First argument value (passed by value) */ localValue1, /* Terminate argument list. */ G_TYPE_INVALID); g_print(PROGNAME ":timerCallback setvalue1 launched\n"); /* Step the local value forward. */ localValue1 += 10; /* Repeat timer later. */ return TRUE; } /** * The test program itself. * * 1) Setup GType/GSignal * 2) Create GMainLoop object * 3) Connect to the Session D-Bus * 4) Create a proxy GObject for the remote Value object * 5) Start a timer that will launch timerCallback once per second. * 6) Run main-loop (forever) */ int main(int argc, char** argv) { DBusGConnection* bus; /* The proxy object. */ DBusGProxy* remoteValue; GMainLoop* mainloop; GError* error = NULL; g_type_init(); mainloop = g_main_loop_new(NULL, FALSE); /* Failure to create the main loop is fatal (for us). */ if (mainloop == NULL) { handleError("Failed to create the mainloop", "Unknown (OOM?)", TRUE); } g_print(PROGNAME ":main Connecting to Session D-Bus.\n"); bus = dbus_g_bus_get(DBUS_BUS_SESSION, &error); if (error != NULL) { handleError("Couldn't connect to the Session bus", error->message, TRUE); } g_print(PROGNAME ":main Creating a GLib proxy object for Value.\n"); remoteValue = dbus_g_proxy_new_for_name(bus, VALUE_SERVICE_NAME, /* name */ VALUE_SERVICE_OBJECT_PATH, /* obj path */ VALUE_SERVICE_INTERFACE /* interface */); if (remoteValue == NULL) { handleError("Couldn't create the proxy object", "Unknown(dbus_g_proxy_new_for_name)", TRUE); } g_print(PROGNAME ":main Starting main loop (first timer in 1s).\n"); g_timeout_add(1000, (GSourceFunc)timerCallback, remoteValue); /* Run the program. */ g_main_loop_run(mainloop); /* Since the main loop is not stopped (by this code), we shouldn't ever get here. The program might abort() for other reasons. */ /* If it does, return failure as exit code. */ return 1; }
F.6 glib-dbus-async/Makefile
glib-dbus-async/Makefile# Similar Makefile than before for the synchronous glib-dbus-example, # but this time for two clients. client-stubs uses the generated stub # functions, client-glib uses the GLib wrapper functions. Comment # verbosity has also been reduced. # Interface XML name (used in multiple targets) interface_xml := value-dbus-interface.xml # Define a list of pkg-config packages we want to use pkg_packages := dbus-1 dbus-glib-1 # Get compilation flags for necessary libraries from pkg-config PKG_CFLAGS := $(shell pkg-config -cflags $(pkg_packages)) # Get linking flags PKG_LDFLAGS := $(shell pkg-config -libs $(pkg_packages)) # Add debugging, full warnings and GLib deprecation ADD_CFLAGS += -g -Wall -DG_DISABLE_DEPRECATED # -DNO_DAEMON : do not daemonize the server (on a separate line so can # be disabled just by commenting the line) ADD_CFLAGS += -DNO_DAEMON # Combine user supplied, additional and pkg-config flags CFLAGS := $(PKG_CFLAGS) $(ADD_CFLAGS) $(CFLAGS) LDFLAGS := $(PKG_LDFLAGS) $(LDFLAGS) # Define a list of generated files so that they can be cleaned as well cleanfiles := value-client-stub.h value-server-stub.h targets = server client-stubs client-glib .PHONY: all clean checkxml all: $(targets) server: server.o $(CC) $^ -o $@ $(LDFLAGS) client-stubs: client-stubs.o $(CC) $^ -o $@ $(LDFLAGS) client-glib: client-glib.o $(CC) $^ -o $@ $(LDFLAGS) server.o: server.c common-defs.h value-server-stub.h $(CC) $(CFLAGS) -DPROGNAME=\"$(basename $@)\" -c $< -o $@ client-stubs.o: client-stubs.c common-defs.h value-client-stub.h $(CC) $(CFLAGS) -DPROGNAME=\"$(basename $@)\" -c $< -o $@ # Note that the GLib client doesn't need the stub code. client-glib.o: client-glib.c common-defs.h $(CC) $(CFLAGS) -DPROGNAME=\"$(basename $@)\" -c $< -o $@ # The stub header dependencies value-server-stub.h: $(interface_xml) dbus-binding-tool -prefix=value_object -mode=glib-server \ $< > $@ value-client-stub.h: $(interface_xml) dbus-binding-tool -prefix=value_object -mode=glib-client \ $< > $@ # XML interface validation checkxml: $(interface_xml) @xmllint -valid -noout $< @echo $< checks out ok clean: $(RM) $(targets) $(cleanfiles) *.o # Changing Makefile will cause rebuild server.o client-stubs.o clients-glib.o: Makefile
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