Simulate EAGAIN in debug mode, every seventh operation. private/mmeeks/eagain-simulation

Hopefully reasonably simple; we perturb the count in the poll to
avoid starving a seventh socket in a poll.

Change-Id: I1a39cc36b9599ffe82186b896c6fd91d792c4127

3 files changed, 59 insertions, 1 deletions

diff --git a/net/Socket.cpp b/net/Socket.cpp
index 4e14d66810..344c0809e5 100644
--- a/net/Socket.cpp
+++ b/net/Socket.cpp
@@ -1,4 +1,3 @@
-
 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
 /*
  * This Source Code Form is subject to the terms of the Mozilla Public
@@ -62,6 +61,32 @@ int Socket::createSocket(Socket::Type type)
 #endif
 }
 
+#ifdef ENABLE_DEBUG
+static std::atomic<long> socketErrorCount;
+
+bool StreamSocket::simulateSocketError(bool)
+{
+    if ((socketErrorCount++ % 7) == 0)
+    {
+        errno = EAGAIN;
+        return true;
+    }
+    else
+        return false;
+}
+
+bool SslStreamSocket::simulateSocketError(bool read)
+{
+    if ((socketErrorCount++ % 7) == 0)
+    {
+        _sslWantsTo = read ? SslWantsTo::Read : SslWantsTo::Write;
+        return true;
+    }
+    else
+        return false;
+}
+#endif
+
 // help with initialization order
 namespace {
     std::vector<int> &getWakeupsArray()
@@ -205,6 +230,11 @@ int SocketPoll::poll(int64_t timeoutMaxMicroS)
     else
         assertCorrectThread();
 
+#ifdef ENABLE_DEBUG
+    // perturb - to rotate errors among several busy sockets.
+    socketErrorCount++;
+#endif
+
     std::chrono::steady_clock::time_point now =
         std::chrono::steady_clock::now();
 
diff --git a/net/Socket.hpp b/net/Socket.hpp
index b8b5cfc2ae..75a0349068 100644
--- a/net/Socket.hpp
+++ b/net/Socket.hpp
@@ -1264,6 +1264,11 @@ protected:
         if (_readType == UseRecvmsgExpectFD)
             return readFD(buf, len, _incomingFD);
 
+#if ENABLE_DEBUG
+        if (simulateSocketError(true))
+            return -1;
+#endif
+
         return ::read(getFD(), buf, len);
 #else
         return fakeSocketRead(getFD(), buf, len);
@@ -1275,6 +1280,10 @@ protected:
     {
         assertCorrectThread();
 #if !MOBILEAPP
+#if ENABLE_DEBUG
+        if (simulateSocketError(false))
+            return -1;
+#endif
         return ::write(getFD(), buf, len);
 #else
         return fakeSocketWrite(getFD(), buf, len);
@@ -1296,6 +1305,12 @@ protected:
         return _socketHandler;
     }
 
+protected:
+#if ENABLE_DEBUG
+    /// Return true and set errno to simulate an error
+    virtual bool simulateSocketError(bool read);
+#endif
+
   private:
     /// Client handling the actual data.
     std::shared_ptr<ProtocolHandlerInterface> _socketHandler;
diff --git a/net/SslSocket.hpp b/net/SslSocket.hpp
index 79415f3c30..0d42f0c9ac 100644
--- a/net/SslSocket.hpp
+++ b/net/SslSocket.hpp
@@ -113,6 +113,10 @@ public:
     {
         assertCorrectThread();
 
+#if ENABLE_DEBUG
+        if (simulateSocketError(true))
+            return -1;
+#endif
         return handleSslState(SSL_read(_ssl, buf, len));
     }
 
@@ -121,6 +125,11 @@ public:
         assertCorrectThread();
 
         assert (len > 0); // Never write 0 bytes.
+
+#if ENABLE_DEBUG
+        if (simulateSocketError(false))
+            return -1;
+#endif
         return handleSslState(SSL_write(_ssl, buf, len));
     }
 
@@ -148,6 +157,10 @@ public:
     }
 
 private:
+#if ENABLE_DEBUG
+    /// Return true and set errno to simulate an error
+    virtual bool simulateSocketError(bool read) override;
+#endif
 
     /// The possible next I/O operation that SSL want to do.
     enum class SslWantsTo