BUG#13987 Cluster: Loss of data nodes can cause high CPU usage from ndb_mgmd

smaller patch for 5.0.

complete patch going to 5.1 due to more intrusiveness for 'list sessions' etc


ndb/include/mgmapi/mgmapi.h:
  add internal get_fd to use in test
ndb/include/util/InputStream.hpp:
  - add this weird startover member to SocketInputStream
      - this helps work out if we've read a newline yet and should start inserting
           into buffer from the start
ndb/src/common/util/InputStream.cpp:
  remove evil, add more.
  
  keep track internally we've retrieved a newline yet (m_startover)
ndb/src/common/util/Parser.cpp:
  change way detecting of NoLine
  
  remove some trailing whitespace that was uglying the place up a bit
ndb/src/common/util/socket_io.cpp:
  Always retrieve data from the OS so that we instantly get EOF on disconnect
  and don't end up spinning looking for a newline.
ndb/src/mgmapi/mgmapi.cpp:
  add internal ndb_mgm_get_fd() for internal testing
  
  handle 'node status' a bit better
ndb/test/ndbapi/testMgm.cpp:
  Add test for MgmApiSession disconnection (mgmd at 100%)
  
  not fully automated due to smaller patch for 5.0
  
  will be complete in 5.1

ndb/include/mgmapi/mgmapi.h

@@ -1071,6 +1071,19 @@ extern "C" {
    */
   int ndb_mgm_end_session(NdbMgmHandle handle);
 
+  /**
+   * ndb_mgm_get_fd
+   *
+   * get the file descriptor of the handle.
+   * INTERNAL ONLY.
+   * USE FOR TESTING. OTHER USES ARE NOT A GOOD IDEA.
+   *
+   * @param  handle NDB management handle
+   * @return handle->socket
+   *
+   */
+  int ndb_mgm_get_fd(NdbMgmHandle handle);
+
   /**
    * Get the node id of the mgm server we're connected to
    */

ndb/include/util/InputStream.hpp

@@ -40,6 +40,7 @@ extern FileInputStream Stdin;
 class SocketInputStream : public InputStream {
   NDB_SOCKET_TYPE m_socket;
   unsigned m_timeout;
+  bool m_startover;
 public:
   SocketInputStream(NDB_SOCKET_TYPE socket, unsigned readTimeout = 1000);
   char* gets(char * buf, int bufLen);

ndb/src/common/util/InputStream.cpp

@@ -37,25 +37,34 @@ FileInputStream::gets(char * buf, int bufLen){
 SocketInputStream::SocketInputStream(NDB_SOCKET_TYPE socket, 
 				     unsigned readTimeout) 
   : m_socket(socket) {
+  m_startover= true;
   m_timeout = readTimeout;
 }
 
 char*
 SocketInputStream::gets(char * buf, int bufLen) {
-  buf[0] = 77;
   assert(bufLen >= 2);
-  int res = readln_socket(m_socket, m_timeout, buf, bufLen - 1);
+  int offset= 0;
+  if(m_startover)
+  {
+    buf[0]= '\0';
+    m_startover= false;
+  }
+  else
+    offset= strlen(buf);
+
+  int res = readln_socket(m_socket, m_timeout, buf+offset, bufLen-offset);
+
+  if(res == 0)
+  {
+    buf[0]=0;
+    return buf;
+  }
+
+  m_startover= true;
+
   if(res == -1)
     return 0;
-  if(res == 0 && buf[0] == 77){ // select return 0
-    buf[0] = 0;
-  } else if(res == 0 && buf[0] == 0){ // only newline
-    buf[0] = '\n';
-    buf[1] = 0;
-  } else {
-    int len = strlen(buf);
-    buf[len + 1] = '\0';
-    buf[len] = '\n';
-  }
+
   return buf;
 }

ndb/src/common/util/Parser.cpp

@@ -158,8 +158,13 @@ ParserImpl::run(Context * ctx, const class Properties ** pDst,
     DBUG_RETURN(false);
   }
 
-  if(ctx->m_currentToken[0] == 0){
+  int last= strlen(ctx->m_currentToken);
+  if(last>0)
+    last--;
+
+  if(ctx->m_currentToken[last] !='\n'){
     ctx->m_status = Parser<Dummy>::NoLine;
+    ctx->m_tokenBuffer[0]= '\0';
     DBUG_RETURN(false);
   }
 

ndb/src/common/util/socket_io.cpp

@@ -75,7 +75,6 @@ readln_socket(NDB_SOCKET_TYPE socket, int timeout_millis,
     return -1;
   }
 
-  buf[0] = 0;
   const int t = recv(socket, buf, buflen, MSG_PEEK);
 
   if(t < 1)
@@ -87,27 +86,28 @@ readln_socket(NDB_SOCKET_TYPE socket, int timeout_millis,
   for(int i=0; i< t;i++)
   {
     if(buf[i] == '\n'){
-      recv(socket, buf, i+1, 0);
-      buf[i] = 0;
+      int r= recv(socket, buf, i+1, 0);
+      buf[i+1]= 0;
+      if(r < 1) {
+        fcntl(socket, F_SETFL, sock_flags);
+        return -1;
+      }
 
       if(i > 0 && buf[i-1] == '\r'){
-        i--;
-        buf[i] = 0;
+        buf[i-1] = '\n';
+        buf[i]= '\0';
       }
 
       fcntl(socket, F_SETFL, sock_flags);
-      return t;
+      return r;
     }
   }
 
-  if(t == (buflen - 1)){
-    recv(socket, buf, t, 0);
-    buf[t] = 0;
+  int r= recv(socket, buf, t, 0);
+  if(r>=0)
+    buf[r] = 0;
   fcntl(socket, F_SETFL, sock_flags);
-    return buflen;
-  }
-
-  return 0;
+  return r;
 }
 
 extern "C"

ndb/src/mgmapi/mgmapi.cpp

@@ -502,6 +502,18 @@ ndb_mgm_connect(NdbMgmHandle handle, int no_retries,
   DBUG_RETURN(0);
 }
 
+/**
+ * Only used for low level testing
+ * Never to be used by end user.
+ * Or anybody who doesn't know exactly what they're doing.
+ */
+extern "C"
+int
+ndb_mgm_get_fd(NdbMgmHandle handle)
+{
+  return handle->socket;
+}
+
 /**
  * Disconnect from a mgm server
  */
@@ -692,21 +704,15 @@ ndb_mgm_get_status(NdbMgmHandle handle)
     SET_ERROR(handle, NDB_MGM_ILLEGAL_SERVER_REPLY, "Probably disconnected");
     return NULL;
   }
-  if(buf[strlen(buf)-1] == '\n')
-    buf[strlen(buf)-1] = '\0';
-
-  if(strcmp("node status", buf) != 0) {
+  if(strcmp("node status\n", buf) != 0) {
     SET_ERROR(handle, NDB_MGM_ILLEGAL_NODE_STATUS, buf);
     return NULL;
   }
-
   if(!in.gets(buf, sizeof(buf)))
   {
     SET_ERROR(handle, NDB_MGM_ILLEGAL_SERVER_REPLY, "Probably disconnected");
     return NULL;
   }
-  if(buf[strlen(buf)-1] == '\n')
-    buf[strlen(buf)-1] = '\0';
 
   BaseString tmp(buf);
   Vector<BaseString> split;
@@ -2280,7 +2286,6 @@ ndb_mgm_check_connection(NdbMgmHandle handle){
   SocketOutputStream out(handle->socket);
   SocketInputStream in(handle->socket, handle->read_timeout);
   char buf[32];
-
   if (out.println("check connection"))
     goto ndb_mgm_check_connection_error;
 
@@ -2490,7 +2495,6 @@ int ndb_mgm_end_session(NdbMgmHandle handle)
 
   SocketInputStream in(handle->socket, handle->read_timeout);
   char buf[32];
-
   in.gets(buf, sizeof(buf));
 
   DBUG_RETURN(0);

ndb/test/ndbapi/testMgm.cpp

@@ -21,6 +21,8 @@
 #include <NdbRestarter.hpp>
 #include <Vector.hpp>
 #include <random.h>
+#include <mgmapi.h>
+#include <mgmapi_debug.h>
 
 int runLoadTable(NDBT_Context* ctx, NDBT_Step* step){
 
@@ -167,6 +169,26 @@ int runTestSingleUserMode(NDBT_Context* ctx, NDBT_Step* step){
   return result;
 }
 
+int runTestApiSession(NDBT_Context* ctx, NDBT_Step* step)
+{
+  char *mgm= ctx->getRemoteMgm();
+
+  NdbMgmHandle h;
+  h= ndb_mgm_create_handle();
+  ndb_mgm_set_connectstring(h, mgm);
+  ndb_mgm_connect(h,0,0,0);
+  int s= ndb_mgm_get_fd(h);
+  write(s,"get",3);
+  ndb_mgm_disconnect(h);
+  ndb_mgm_destroy_handle(&h);
+  /** NOTE: WE CANNOT REALLY TEST ANYTHING in 5.0
+   *
+   * a more conservative patch for 5.0, full get and list
+   * sessions in 5.1.
+   *
+   * This is kept so that we can at least manually test easily
+   */
+}
 
 
 NDBT_TESTSUITE(testMgm);
@@ -175,6 +197,11 @@ TESTCASE("SingleUserMode",
   INITIALIZER(runTestSingleUserMode);
   FINALIZER(runClearTable);
 }
+TESTCASE("ApiSessionFailure",
+	 "Test failures in MGMAPI session"){
+  INITIALIZER(runTestApiSession);
+
+}
 NDBT_TESTSUITE_END(testMgm);
 
 int main(int argc, const char** argv){