FlightSim-Streaming/XPlaneConnectCSP
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Minimize sendUDP and readUDP Socket Timeout Delays

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sendUDP and readUDP were using longer than necessary socket timeouts that may add to process time delay and stuttering.  They were also using different values between Window and Linux/Mac.  The timeouts are now standardized for all versions.
This commit is contained in:
Norman Princen
2020-05-12 09:57:38 -07:00
committed by GitHub
parent b69a7e2bab
commit 581675818b
1 changed files with 14 additions and 12 deletions
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26
C/src/xplaneConnect.c
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@@ -117,13 +117,16 @@ XPCSocket aopenUDP(const char *xpIP, unsigned short xpPort, unsigned short port)
exit(EXIT_FAILURE);
}
// Set timeout to 100ms
// Set socket timeout period for sendUDP to 1 millisecond
// Without this, playback may become choppy due to process blocking
#ifdef _WIN32
DWORD timeout = 100;
// Minimum socket timeout in Windows is 1 millisecond (0 makes it blocking)
DWORD timeout = 1;
#else
// Set socket timeout to 1 millisecond = 1,000 microseconds to make it the same as Windows (0 makes it blocking)
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = 250000;
timeout.tv_usec = 1000;
#endif
if (setsockopt(sock.sock, SOL_SOCKET, SO_RCVTIMEO, (char*)&timeout, sizeof(timeout)) < 0)
{
@@ -188,13 +191,13 @@ int sendUDP(XPCSocket sock, char buffer[], int len)
/// \returns If an error occurs, a negative number. Otherwise, the number of bytes read.
int readUDP(XPCSocket sock, char buffer[], int len)
{
#ifdef _WIN32
// Windows readUDP needs the select command- minimum timeout is 1ms.
// Without this playback becomes choppy
// For readUDP, use the select command - minimum timeout of 0 makes it polling.
// Without this, playback may become choppy due to process blocking
// Definitions
FD_SET stReadFDS;
FD_SET stExceptFDS;
struct timeval tv;
// Setup for Select
FD_ZERO(&stReadFDS);
@@ -202,9 +205,10 @@ int readUDP(XPCSocket sock, char buffer[], int len)
FD_ZERO(&stExceptFDS);
FD_SET(sock.sock, &stExceptFDS);
struct timeval tv;
// Set timeout period for select to 0.05 sec = 50 milliseconds = 50,000 microseconds (0 makes it polling)
// TO DO - This could be set to 0 if a message handling system were implemented, like in the plugin.
tv.tv_sec = 0;
tv.tv_usec = 100000;
tv.tv_usec = 50000;
// Select Command
int status = select(-1, &stReadFDS, (FD_SET*)0, &stExceptFDS, &tv);
@@ -218,11 +222,9 @@ int readUDP(XPCSocket sock, char buffer[], int len)
// No data
return 0;
}
// If no error: Read Data
status = recv(sock.sock, buffer, len, 0);
#else
// For apple or linux-just read - will timeout in 0.5 ms
int status = (int)recv(sock.sock, buffer, len, 0);
#endif
if (status < 0)
{
printError("readUDP", "Error reading socket");