Move socket watch APIs into System::Layer

#### Problem

Transitionally, `System::Layer` operations are provided by a
configuration-specific `WatchableEventManager`, but they are not yet
sufficiently aligned to convert to abstract and implementation classes.

Part of project-chip#7715 Virtualize System and Inet interfaces

#### Change overview

- Move socket event watch APIs into `System::Layer`.
- Remove `WatchableSocket` and its include-file hack that allowed
  implementation-specific state to be contained directly in EndPoints.
- Revise the select() implementation to use an internal pool for watch
  state in place of the EndPoint-embedded WatchableSocket.
- Revise the libevent sample implementation to use libevent timers
  directly instead of the System::Timer pool. The libevent
  implementation uses STL containers with heap-allocated state for the
  sake of being different from the select()-based implementation.

#### Testing

CI; no change to functionality should is expected.

examples/minimal-mdns/client.cpp

@@ -29,7 +29,6 @@
 #include <support/CHIPArgParser.hpp>
 #include <support/CHIPMem.h>
 #include <system/SystemPacketBuffer.h>
-#include <system/SystemTimer.h>
 
 #include "AllInterfaceListener.h"
 #include "PacketReporter.h"

examples/minimal-mdns/server.cpp

@@ -35,7 +35,6 @@
 #include <support/CHIPArgParser.hpp>
 #include <support/CHIPMem.h>
 #include <system/SystemPacketBuffer.h>
-#include <system/SystemTimer.h>
 
 #include "AllInterfaceListener.h"
 #include "PacketReporter.h"

examples/platform/nrfconnect/util/test/TestInetCommon.cpp

@@ -46,7 +46,6 @@
 #include <support/CHIPMem.h>
 #include <support/ErrorStr.h>
 #include <support/ScopedBuffer.h>
-#include <system/SystemTimer.h>
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
 #include <arpa/inet.h>
@@ -114,7 +113,7 @@ void ServiceEvents(struct ::timeval & aSleepTime)
     FD_ZERO(&exceptFDs);
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-    if (gSystemLayer.State() == System::kLayerState_Initialized)
+    if (gSystemLayer.State() == System::LayerState::kInitialized)
         gSystemLayer.PrepareSelect(numFDs, &readFDs, &writeFDs, &exceptFDs, aSleepTime);
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
 
@@ -131,7 +130,7 @@ void ServiceEvents(struct ::timeval & aSleepTime)
     }
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
 
-    if (gSystemLayer.State() == System::kLayerState_Initialized)
+    if (gSystemLayer.State() == System::LayerState::kInitialized)
     {
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS

src/app/EventManagement.cpp

@@ -24,7 +24,6 @@
 #include <support/CodeUtils.h>
 #include <support/ErrorStr.h>
 #include <support/logging/CHIPLogging.h>
-#include <system/SystemTimer.h>
 
 using namespace chip::TLV;
 

src/app/tests/TestReadInteraction.cpp

@@ -40,7 +40,6 @@
 #include <support/ErrorStr.h>
 #include <support/UnitTestRegistration.h>
 #include <system/SystemPacketBuffer.h>
-#include <system/SystemTimer.h>
 #include <system/TLVPacketBufferBackingStore.h>
 #include <transport/SecureSessionMgr.h>
 #include <transport/raw/UDP.h>

src/app/tests/integration/MockEvents.cpp

@@ -31,7 +31,6 @@
 #include <protocols/secure_channel/PASESession.h>
 #include <support/ErrorStr.h>
 #include <system/SystemPacketBuffer.h>
-#include <system/SystemTimer.h>
 #include <transport/SecureSessionMgr.h>
 
 static uint64_t kLivenessDeviceStatus = chip::TLV::ContextTag(1);

src/app/util/af-event.cpp

@@ -43,7 +43,6 @@
 #include <app/util/attribute-storage.h>
 
 #include <platform/CHIPDeviceLayer.h>
-#include <system/SystemTimer.h>
 
 #define EMBER_MAX_EVENT_CONTROL_DELAY_MS (UINT32_MAX / 2)
 #define EMBER_MAX_EVENT_CONTROL_DELAY_QS (EMBER_MAX_EVENT_CONTROL_DELAY_MS >> 8)

src/inet/EndPointBasis.cpp

@@ -39,7 +39,7 @@ void EndPointBasis::InitEndPointBasis(InetLayer & aInetLayer, void * aAppState)
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-    (void) mSocket.Init(aInetLayer.SystemLayer()->WatchableEventsManager());
+    mSocket = INET_INVALID_SOCKET_FD;
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
 }
 

src/inet/EndPointBasis.h

@@ -35,7 +35,7 @@
 #include <support/DLLUtil.h>
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-#include <system/WatchableSocket.h>
+#include <system/SocketEvents.h>
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
 
 #if CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
@@ -97,9 +97,10 @@ class DLL_EXPORT EndPointBasis : public InetLayerBasis
 #endif
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-    System::WatchableSocket mSocket; /**< Encapsulated socket descriptor. */
-    IPAddressType mAddrType;         /**< Protocol family, i.e. IPv4 or IPv6. */
-#endif                               // CHIP_SYSTEM_CONFIG_USE_SOCKETS
+    int mSocket;                    /**< Encapsulated socket descriptor. */
+    IPAddressType mAddrType;        /**< Protocol family, i.e. IPv4 or IPv6. */
+    System::SocketWatchToken mWatch; /**< Socket event watcher */
+#endif                              // CHIP_SYSTEM_CONFIG_USE_SOCKETS
 
 #if CHIP_SYSTEM_CONFIG_USE_LWIP
     /** Encapsulated LwIP protocol control block */
@@ -145,7 +146,7 @@ inline bool EndPointBasis::IsNetworkFrameworkEndPoint(void) const
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
 inline bool EndPointBasis::IsSocketsEndPoint() const
 {
-    return mSocket.HasFD();
+    return mSocket != INET_INVALID_SOCKET_FD;
 }
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
 

src/inet/IPEndPointBasis.cpp

@@ -389,7 +389,7 @@ CHIP_ERROR IPEndPointBasis::SetMulticastLoopback(IPVersion aIPVersion, bool aLoo
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-    lRetval = SocketsSetMulticastLoopback(mSocket.GetFD(), aIPVersion, aLoopback);
+    lRetval = SocketsSetMulticastLoopback(mSocket, aIPVersion, aLoopback);
     SuccessOrExit(lRetval);
 
 exit:
@@ -449,7 +449,7 @@ CHIP_ERROR IPEndPointBasis::JoinMulticastGroup(InterfaceId aInterfaceId, const I
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-        lRetval = SocketsIPv4JoinLeaveMulticastGroup(mSocket.GetFD(), aInterfaceId, aAddress, IP_ADD_MEMBERSHIP);
+        lRetval = SocketsIPv4JoinLeaveMulticastGroup(mSocket, aInterfaceId, aAddress, IP_ADD_MEMBERSHIP);
         SuccessOrExit(lRetval);
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
     }
@@ -474,7 +474,7 @@ CHIP_ERROR IPEndPointBasis::JoinMulticastGroup(InterfaceId aInterfaceId, const I
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-        lRetval = SocketsIPv6JoinMulticastGroup(mSocket.GetFD(), aInterfaceId, aAddress);
+        lRetval = SocketsIPv6JoinMulticastGroup(mSocket, aInterfaceId, aAddress);
         SuccessOrExit(lRetval);
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
     }
@@ -541,7 +541,7 @@ CHIP_ERROR IPEndPointBasis::LeaveMulticastGroup(InterfaceId aInterfaceId, const
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-        lRetval = SocketsIPv4JoinLeaveMulticastGroup(mSocket.GetFD(), aInterfaceId, aAddress, IP_DROP_MEMBERSHIP);
+        lRetval = SocketsIPv4JoinLeaveMulticastGroup(mSocket, aInterfaceId, aAddress, IP_DROP_MEMBERSHIP);
         SuccessOrExit(lRetval);
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
     }
@@ -566,7 +566,7 @@ CHIP_ERROR IPEndPointBasis::LeaveMulticastGroup(InterfaceId aInterfaceId, const
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-        lRetval = SocketsIPv6LeaveMulticastGroup(mSocket.GetFD(), aInterfaceId, aAddress);
+        lRetval = SocketsIPv6LeaveMulticastGroup(mSocket, aInterfaceId, aAddress);
         SuccessOrExit(lRetval);
 #endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
     }
@@ -693,21 +693,21 @@ CHIP_ERROR IPEndPointBasis::Bind(IPAddressType aAddressType, const IPAddress & a
         }
         sa.sin6_scope_id = static_cast<decltype(sa.sin6_scope_id)>(aInterfaceId);
 
-        if (bind(mSocket.GetFD(), reinterpret_cast<const sockaddr *>(&sa), static_cast<unsigned>(sizeof(sa))) != 0)
+        if (bind(mSocket, reinterpret_cast<const sockaddr *>(&sa), static_cast<unsigned>(sizeof(sa))) != 0)
             lRetval = chip::System::MapErrorPOSIX(errno);
 
             // Instruct the kernel that any messages to multicast destinations should be
             // sent down the interface specified by the caller.
 #ifdef IPV6_MULTICAST_IF
         if (lRetval == CHIP_NO_ERROR)
-            setsockopt(mSocket.GetFD(), IPPROTO_IPV6, IPV6_MULTICAST_IF, &aInterfaceId, sizeof(aInterfaceId));
+            setsockopt(mSocket, IPPROTO_IPV6, IPV6_MULTICAST_IF, &aInterfaceId, sizeof(aInterfaceId));
 #endif // defined(IPV6_MULTICAST_IF)
 
             // Instruct the kernel that any messages to multicast destinations should be
             // set with the configured hop limit value.
 #ifdef IPV6_MULTICAST_HOPS
         int hops = INET_CONFIG_IP_MULTICAST_HOP_LIMIT;
-        setsockopt(mSocket.GetFD(), IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops));
+        setsockopt(mSocket, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops));
 #endif // defined(IPV6_MULTICAST_HOPS)
     }
 #if INET_CONFIG_ENABLE_IPV4
@@ -722,26 +722,26 @@ CHIP_ERROR IPEndPointBasis::Bind(IPAddressType aAddressType, const IPAddress & a
         sa.sin_port   = htons(aPort);
         sa.sin_addr   = aAddress.ToIPv4();
 
-        if (bind(mSocket.GetFD(), reinterpret_cast<const sockaddr *>(&sa), static_cast<unsigned>(sizeof(sa))) != 0)
+        if (bind(mSocket, reinterpret_cast<const sockaddr *>(&sa), static_cast<unsigned>(sizeof(sa))) != 0)
             lRetval = chip::System::MapErrorPOSIX(errno);
 
             // Instruct the kernel that any messages to multicast destinations should be
             // sent down the interface to which the specified IPv4 address is bound.
 #ifdef IP_MULTICAST_IF
         if (lRetval == CHIP_NO_ERROR)
-            setsockopt(mSocket.GetFD(), IPPROTO_IP, IP_MULTICAST_IF, &sa, sizeof(sa));
+            setsockopt(mSocket, IPPROTO_IP, IP_MULTICAST_IF, &sa, sizeof(sa));
 #endif // defined(IP_MULTICAST_IF)
 
             // Instruct the kernel that any messages to multicast destinations should be
             // set with the configured hop limit value.
 #ifdef IP_MULTICAST_TTL
         int ttl = INET_CONFIG_IP_MULTICAST_HOP_LIMIT;
-        setsockopt(mSocket.GetFD(), IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
+        setsockopt(mSocket, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
 #endif // defined(IP_MULTICAST_TTL)
 
         // Allow socket transmitting broadcast packets.
         if (lRetval == CHIP_NO_ERROR)
-            setsockopt(mSocket.GetFD(), SOL_SOCKET, SO_BROADCAST, &enable, sizeof(enable));
+            setsockopt(mSocket, SOL_SOCKET, SO_BROADCAST, &enable, sizeof(enable));
     }
 #endif // INET_CONFIG_ENABLE_IPV4
     else
@@ -758,7 +758,7 @@ CHIP_ERROR IPEndPointBasis::BindInterface(IPAddressType aAddressType, InterfaceI
     if (aInterfaceId == INET_NULL_INTERFACEID)
     {
         // Stop interface-based filtering.
-        if (setsockopt(mSocket.GetFD(), SOL_SOCKET, SO_BINDTODEVICE, "", 0) == -1)
+        if (setsockopt(mSocket, SOL_SOCKET, SO_BINDTODEVICE, "", 0) == -1)
         {
             lRetval = chip::System::MapErrorPOSIX(errno);
         }
@@ -774,7 +774,7 @@ CHIP_ERROR IPEndPointBasis::BindInterface(IPAddressType aAddressType, InterfaceI
         }
 
         if (lRetval == CHIP_NO_ERROR &&
-            setsockopt(mSocket.GetFD(), SOL_SOCKET, SO_BINDTODEVICE, lInterfaceName, socklen_t(strlen(lInterfaceName))) == -1)
+            setsockopt(mSocket, SOL_SOCKET, SO_BINDTODEVICE, lInterfaceName, socklen_t(strlen(lInterfaceName))) == -1)
         {
             lRetval = chip::System::MapErrorPOSIX(errno);
         }
@@ -907,7 +907,7 @@ CHIP_ERROR IPEndPointBasis::SendMsg(const IPPacketInfo * aPktInfo, chip::System:
     }
 
     // Send IP packet.
-    const ssize_t lenSent = sendmsg(mSocket.GetFD(), &msgHeader, 0);
+    const ssize_t lenSent = sendmsg(mSocket, &msgHeader, 0);
     if (lenSent == -1)
         return chip::System::MapErrorPOSIX(errno);
     if (lenSent != aBuffer->DataLength())
@@ -917,7 +917,7 @@ CHIP_ERROR IPEndPointBasis::SendMsg(const IPPacketInfo * aPktInfo, chip::System:
 
 CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int aProtocol)
 {
-    if (!mSocket.HasFD())
+    if (mSocket == INET_INVALID_SOCKET_FD)
     {
         const int one = 1;
         int family;
@@ -938,10 +938,10 @@ CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int
             return INET_ERROR_WRONG_ADDRESS_TYPE;
         }
 
-        const int fd = ::socket(family, aType, aProtocol);
-        if (fd == -1)
+        mSocket = ::socket(family, aType, aProtocol);
+        if (mSocket == -1)
             return chip::System::MapErrorPOSIX(errno);
-        ReturnErrorOnFailure(mSocket.Attach(fd));
+        ReturnErrorOnFailure(SystemLayer().StartWatchingSocket(mSocket, &mWatch));
 
         mAddrType = aAddressType;
 
@@ -954,11 +954,11 @@ CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int
         // logic up to check for implementations of these options and
         // to provide appropriate HAVE_xxxxx definitions accordingly.
 
-        int res = setsockopt(mSocket.GetFD(), SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+        int res = setsockopt(mSocket, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
         static_cast<void>(res);
 
 #ifdef SO_REUSEPORT
-        res = setsockopt(mSocket.GetFD(), SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+        res = setsockopt(mSocket, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
         if (res != 0)
         {
             ChipLogError(Inet, "SO_REUSEPORT failed: %d", errno);
@@ -972,7 +972,7 @@ CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int
 #ifdef IPV6_V6ONLY
         if (aAddressType == kIPAddressType_IPv6)
         {
-            res = setsockopt(mSocket.GetFD(), IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
+            res = setsockopt(mSocket, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
             if (res != 0)
             {
                 ChipLogError(Inet, "IPV6_V6ONLY failed: %d", errno);
@@ -984,7 +984,7 @@ CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int
 #ifdef IP_PKTINFO
         if (aAddressType == kIPAddressType_IPv4)
         {
-            res = setsockopt(mSocket.GetFD(), IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
+            res = setsockopt(mSocket, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
             if (res != 0)
             {
                 ChipLogError(Inet, "IP_PKTINFO failed: %d", errno);
@@ -996,7 +996,7 @@ CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int
 #ifdef IPV6_RECVPKTINFO
         if (aAddressType == kIPAddressType_IPv6)
         {
-            res = setsockopt(mSocket.GetFD(), IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
+            res = setsockopt(mSocket, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
             if (res != 0)
             {
                 ChipLogError(Inet, "IPV6_PKTINFO failed: %d", errno);
@@ -1010,7 +1010,7 @@ CHIP_ERROR IPEndPointBasis::GetSocket(IPAddressType aAddressType, int aType, int
         // SIGPIPEs on unconnected UDP sockets.
 #ifdef SO_NOSIGPIPE
         {
-            res = setsockopt(mSocket.GetFD(), SOL_SOCKET, SO_NOSIGPIPE, &one, sizeof(one));
+            res = setsockopt(mSocket, SOL_SOCKET, SO_NOSIGPIPE, &one, sizeof(one));
             if (res != 0)
             {
                 ChipLogError(Inet, "SO_NOSIGPIPE failed: %d", errno);
@@ -1058,7 +1058,7 @@ void IPEndPointBasis::HandlePendingIO(uint16_t aPort)
         msgHeader.msg_control    = controlData;
         msgHeader.msg_controllen = sizeof(controlData);
 
-        ssize_t rcvLen = recvmsg(mSocket.GetFD(), &msgHeader, MSG_DONTWAIT);
+        ssize_t rcvLen = recvmsg(mSocket, &msgHeader, MSG_DONTWAIT);
 
         if (rcvLen < 0)
         {

src/inet/InetLayer.cpp

@@ -32,7 +32,7 @@
  *        * Raw network transport
  *
  *      For BSD/POSIX Sockets (CHIP_SYSTEM_CONFIG_USE_SOCKETS), event readiness
- *      notification is handled via file descriptors, using System::WatchableSocket.
+ *      notification is handled via file descriptors, using a System::Layer API.
  *
  *      For LwIP (CHIP_SYSTEM_CONFIG_USE_LWIP), event readiness notification is handled
  *      via events / messages and platform- and system-specific hooks for the event
@@ -49,8 +49,6 @@
 
 #include <platform/LockTracker.h>
 
-#include <system/SystemTimer.h>
-
 #include <support/CodeUtils.h>
 #include <support/logging/CHIPLogging.h>