[utils] unify mainloop interface (#719)

This commit unifies that mainloop interface to always use the
MainloopContext structure rather than fd sets. We also define a
MainloopProcessor interface to ensure that each module defines exactly
the same mainloop processing methods.

2 files changed, 18 insertions, 34 deletions

diff --git a/src/dbus/server/dbus_agent.cpp b/src/dbus/server/dbus_agent.cpp
index 5526e4fd..25c17a56 100644
--- a/src/dbus/server/dbus_agent.cpp
+++ b/src/dbus/server/dbus_agent.cpp
@@ -84,18 +84,14 @@ void DBusAgent::RemoveDBusWatch(struct DBusWatch *aWatch, void *aContext)
     static_cast<DBusAgent *>(aContext)->mWatches.erase(aWatch);
 }
 
-void DBusAgent::UpdateFdSet(fd_set &        aReadFdSet,
-                            fd_set &        aWriteFdSet,
-                            fd_set &        aErrorFdSet,
-                            int &           aMaxFd,
-                            struct timeval &aTimeOut)
+void DBusAgent::Update(MainloopContext &aMainloop)
 {
     unsigned int flags;
     int          fd;
 
     if (dbus_connection_get_dispatch_status(mConnection.get()) == DBUS_DISPATCH_DATA_REMAINS)
     {
-        aTimeOut = {0, 0};
+        aMainloop.mTimeout = {0, 0};
     }
 
     for (const auto &watch : mWatches)
@@ -115,24 +111,21 @@ void DBusAgent::UpdateFdSet(fd_set &        aReadFdSet,
 
         if (flags & DBUS_WATCH_READABLE)
         {
-            FD_SET(fd, &aReadFdSet);
+            FD_SET(fd, &aMainloop.mReadFdSet);
         }
 
         if ((flags & DBUS_WATCH_WRITABLE))
         {
-            FD_SET(fd, &aWriteFdSet);
+            FD_SET(fd, &aMainloop.mWriteFdSet);
         }
 
-        FD_SET(fd, &aErrorFdSet);
+        FD_SET(fd, &aMainloop.mErrorFdSet);
 
-        if (fd > aMaxFd)
-        {
-            aMaxFd = fd;
-        }
+        aMainloop.mMaxFd = std::max(aMainloop.mMaxFd, fd);
     }
 }
 
-void DBusAgent::Process(const fd_set &aReadFdSet, const fd_set &aWriteFdSet, const fd_set &aErrorFdSet)
+void DBusAgent::Process(const MainloopContext &aMainloop)
 {
     unsigned int flags;
     int          fd;
@@ -152,17 +145,17 @@ void DBusAgent::Process(const fd_set &aReadFdSet, const fd_set &aWriteFdSet, con
             continue;
         }
 
-        if ((flags & DBUS_WATCH_READABLE) && !FD_ISSET(fd, &aReadFdSet))
+        if ((flags & DBUS_WATCH_READABLE) && !FD_ISSET(fd, &aMainloop.mReadFdSet))
         {
             flags &= static_cast<unsigned int>(~DBUS_WATCH_READABLE);
         }
 
-        if ((flags & DBUS_WATCH_WRITABLE) && !FD_ISSET(fd, &aWriteFdSet))
+        if ((flags & DBUS_WATCH_WRITABLE) && !FD_ISSET(fd, &aMainloop.mWriteFdSet))
         {
             flags &= static_cast<unsigned int>(~DBUS_WATCH_WRITABLE);
         }
 
-        if (FD_ISSET(fd, &aErrorFdSet))
+        if (FD_ISSET(fd, &aMainloop.mErrorFdSet))
         {
             flags |= DBUS_WATCH_ERROR;
         }
diff --git a/src/dbus/server/dbus_agent.hpp b/src/dbus/server/dbus_agent.hpp
index f75729a2..b67f2424 100644
--- a/src/dbus/server/dbus_agent.hpp
+++ b/src/dbus/server/dbus_agent.hpp
@@ -39,6 +39,7 @@
 #include <string>
 #include <sys/select.h>
 
+#include "common/mainloop.hpp"
 #include "dbus/common/dbus_message_helper.hpp"
 #include "dbus/common/dbus_resources.hpp"
 #include "dbus/server/dbus_object.hpp"
@@ -49,7 +50,7 @@
 namespace otbr {
 namespace DBus {
 
-class DBusAgent
+class DBusAgent : public MainloopProcessor
 {
 public:
     /**
@@ -70,30 +71,20 @@ public:
     otbrError Init(void);
 
     /**
-     * This method performs the dbus select update.
+     * This method updates the mainloop context.
      *
-     * @param[out]      aReadFdSet   The read file descriptors.
-     * @param[out]      aWriteFdSet  The write file descriptors.
-     * @param[out]      aErorFdSet   The error file descriptors.
-     * @param[inout]    aMaxFd       The max file descriptor.
-     * @param[inout]    aTimeOut     The select timeout.
+     * @param[inout]  aMainloop  A reference to the mainloop to be updated.
      *
      */
-    void UpdateFdSet(fd_set &        aReadFdSet,
-                     fd_set &        aWriteFdSet,
-                     fd_set &        aErrorFdSet,
-                     int &           aMaxFd,
-                     struct timeval &aTimeOut);
+    void Update(MainloopContext &aMainloop) override;
 
     /**
-     * This method processes the dbus I/O.
+     * This method processes mainloop events.
      *
-     * @param[in]       aReadFdSet   The read file descriptors.
-     * @param[in]       aWriteFdSet  The write file descriptors.
-     * @param[in]       aErorFdSet   The error file descriptors.
+     * @param[in]  aMainloop  A reference to the mainloop context.
      *
      */
-    void Process(const fd_set &aReadFdSet, const fd_set &aWriteFdSet, const fd_set &aErrorFdSet);
+    void Process(const MainloopContext &aMainloop) override;
 
 private:
     static dbus_bool_t AddDBusWatch(struct DBusWatch *aWatch, void *aContext);