snoop_listen: Add constructors for SnoopListen
Provide two additional constructors for SnoopListen, one that takes
any std::function that operates on sdbusplus message, and another one
that takes std::function that operates on the uint64_t postcode. This
allows user to easily register a POST code handler without writing much
of the boiler plate code.
example.cpp is also converted to use the new constructor.
Tested:
'snooper' program compiled from example.cpp behaves correctly.
Change-Id: I20dc4fa5067e836d3cfa8ebb616a131f38a93a30
Signed-off-by: Kun Yi <kunyi731@gmail.com>
diff --git a/example.cpp b/example.cpp
index 55bd4ed..6754b0e 100644
--- a/example.cpp
+++ b/example.cpp
@@ -19,35 +19,39 @@
#include <iostream>
#include <memory>
-#include <sdbusplus/bus.hpp>
-#include <sdbusplus/message.hpp>
-#include <sdbusplus/server.hpp>
+#include "lpcsnoop/snoop_listen.hpp"
-#include "lpcsnoop/snoop.hpp"
-
-/*
- * Handle incoming dbus signal we care about.
- */
-static int DbusHandleSignal(sd_bus_message* msg, void* data, sd_bus_error* err);
-
-/*
- * Get the match signal for dbus.
- */
-static std::string GetMatch(void);
-
-// Example object that listens for dbus updates.
-class SnoopListen
+/* Example PostCode handler which simply prints them */
+static void printPostcode(uint64_t postcode)
{
- public:
- SnoopListen(sdbusplus::bus::bus& bus) :
- _bus(bus), _signal(bus, GetMatch().c_str(), DbusHandleSignal, this)
- {
- }
+ /* Print output to verify the example program is receiving values. */
+ std::printf("recv: 0x%" PRIx64 "\n", postcode);
+}
- private:
- sdbusplus::bus::bus& _bus;
- sdbusplus::server::match::match _signal;
-};
+/*
+ * One can also specify custom handler that operates on
+ * sdbusplus::message::message type and pass them to constructor.
+ * e.g.
+ *
+ * static void PrintMessageMap(sdbusplus::message::message& m)
+ * {
+ * using sdbusplus::message::variant_ns::get;
+ * std::string messageBusName;
+ * std::map<std::string, sdbusplus::message::variant<uint64_t>>
+ * messageData;
+ *
+ * m.read(messageBusName, messageData);
+ *
+ * std::cout << "Got message from " << messageBusName << std::endl;
+ * for (const auto& kv : messageData)
+ * {
+ * std::cout << "Key: " << kv.first << std::endl;
+ * std::cout << "Value: " << get<uint64_t>(kv.second) << std::endl;
+ * }
+ * }
+ *
+ * lpcsnoop::SnoopListen snoop(ListenBus, PrintMessageMap);
+ */
/*
* This is the entry point for the application.
@@ -58,7 +62,7 @@
int main(int argc, char* argv[])
{
auto ListenBus = sdbusplus::bus::new_default();
- SnoopListen snoop(ListenBus);
+ lpcsnoop::SnoopListen snoop(ListenBus, printPostcode);
while (true)
{
@@ -68,34 +72,3 @@
return 0;
}
-
-static int DbusHandleSignal(sd_bus_message* msg, void* data, sd_bus_error* err)
-{
- auto sdbpMsg = sdbusplus::message::message(msg);
-
- std::string msgSensor, busName{SNOOP_BUSNAME};
- std::map<std::string, sdbusplus::message::variant<uint64_t>> msgData;
- sdbpMsg.read(msgSensor, msgData);
-
- if (msgSensor == busName)
- {
- auto valPropMap = msgData.find("Value");
- if (valPropMap != msgData.end())
- {
- uint64_t rawValue = sdbusplus::message::variant_ns::get<uint64_t>(
- valPropMap->second);
-
- /* Print output to verify the example program is receiving values.
- */
- std::printf("recv: 0x%" PRIx64 "\n", rawValue);
- }
- }
-
- return 0;
-}
-
-static std::string GetMatch(void)
-{
- return "type='signal',interface='org.freedesktop.DBus.Properties',"
- "member='PropertiesChanged',path='" SNOOP_OBJECTPATH "'";
-}
diff --git a/lpcsnoop/snoop_listen.hpp b/lpcsnoop/snoop_listen.hpp
index 15b8c0f..4d0ef36 100644
--- a/lpcsnoop/snoop_listen.hpp
+++ b/lpcsnoop/snoop_listen.hpp
@@ -22,26 +22,39 @@
namespace lpcsnoop
{
-
-using DbusSignalHandler = int (*)(sd_bus_message*, void*, sd_bus_error*);
+using sdbusplus::message::variant_ns::get;
/* Returns matching string for what signal to listen on Dbus */
static const std::string GetMatchRule()
{
- return "type='signal',"
- "interface='org.freedesktop.DBus.Properties',"
- "member='PropertiesChanged',"
- "path='" SNOOP_OBJECTPATH "'";
+ using namespace sdbusplus::bus::match::rules;
+
+ return type::signal() + interface("org.freedesktop.DBus.Properties") +
+ member("PropertiesChanged") + path(SNOOP_OBJECTPATH);
}
class SnoopListen
{
+ using message_handler_t = std::function<void(sdbusplus::message::message&)>;
+ using postcode_handler_t = std::function<void(uint64_t)>;
+
public:
- SnoopListen(sdbusplus::bus::bus& busIn, DbusSignalHandler handler) :
+ SnoopListen(sdbusplus::bus::bus& busIn, sd_bus_message_handler_t handler) :
bus(busIn), signal(busIn, GetMatchRule().c_str(), handler, this)
{
}
+ SnoopListen(sdbusplus::bus::bus& busIn, message_handler_t handler) :
+ bus(busIn), signal(busIn, GetMatchRule(), handler)
+ {
+ }
+
+ SnoopListen(sdbusplus::bus::bus& busIn, postcode_handler_t handler) :
+ SnoopListen(busIn, std::bind(defaultMessageHandler, handler,
+ std::placeholders::_1))
+ {
+ }
+
SnoopListen() = delete; // no default constructor
~SnoopListen() = default;
SnoopListen(const SnoopListen&) = delete;
@@ -52,6 +65,27 @@
private:
sdbusplus::bus::bus& bus;
sdbusplus::server::match::match signal;
+
+ /*
+ * Default message handler which listens to published messages on snoop
+ * DBus path, and calls the given postcode_handler on each value received.
+ */
+ static void defaultMessageHandler(postcode_handler_t& handler,
+ sdbusplus::message::message& m)
+ {
+ std::string messageBusName;
+ std::map<std::string, sdbusplus::message::variant<uint64_t>>
+ messageData;
+ constexpr char propertyKey[] = "Value";
+
+ m.read(messageBusName, messageData);
+
+ if (messageBusName == SNOOP_BUSNAME &&
+ messageData.find(propertyKey) != messageData.end())
+ {
+ handler(get<uint64_t>(messageData[propertyKey]));
+ }
+ }
};
} // namespace lpcsnoop