/**
* Given a snap (likely read from a log) read a value as a double.
* Upon failure will exit the program with error code EXIT_FAILURE.
*
*
* @param name The name of the variable to read in Web100/Web10G.
* @param snap A Web100/Web10G snap
* @param group A Web100 group - ignored by Web10G should be NULL
* @param agent A Web100 agent - ignored by Web10G should be NULL
*
* @return The value of 'name' covnerted to a double.
*/
double tcp_stat_read_double(const char * name, tcp_stat_snap* snap,
tcp_stat_group* group, tcp_stat_agent* agent) {
#if USE_WEB100
web100_var* var;
char buf[256];
#elif USE_WEB10G
estats_val val;
#endif
#if USE_WEB100
if ((web100_agent_find_var_and_group(agent, name, &group,
&var)) != WEB100_ERR_SUCCESS) {
web100_perror("web100_agent_find_var_and_group");
exit(EXIT_FAILURE);
}
if ((web100_snap_read(var, snap, buf)) != WEB100_ERR_SUCCESS) {
web100_perror("web100_snap_read");
exit(EXIT_FAILURE);
}
return atof(
web100_value_to_text(web100_get_var_type(var),
buf));
#elif USE_WEB10G
int vartype = ESTATS_UNSIGNED32;
/* ELAPSED_TIME not working in kernel patch, so use time on the
* snap */
if (strcmp(name, ELAPSED_TIME) == 0) {
val.masked = 0;
val.uv32 = snap->tv.sec * 1000000 + snap->tv.usec - start_time;
} else {
vartype = web10g_find_val(snap, name, &val);
if (vartype == -1) {
printf("Bad vartype tcp_stat_read_double %s\n", name);
exit(EXIT_FAILURE);
}
}
switch (vartype) {
case ESTATS_UNSIGNED64:
return (double) val.uv64;
case ESTATS_UNSIGNED32:
return (double) val.uv32;
case ESTATS_SIGNED32:
return (double) val.sv32;
case ESTATS_UNSIGNED16:
return (double) val.uv16;
case ESTATS_UNSIGNED8:
return (double) val.uv8;
}
fprintf(stderr, "Bad vartype tcp_stat_read_double %s\n", name);
exit(EXIT_FAILURE);
#endif
}
/**
* Count the CWND peaks from a snapshot and record the minimal and maximum one.
* Also record the number of transitions between increasing or decreasing
* trends of the values.
* @param agent Web100 agent used to track the connection
* @param peaks Structure containing CWND peaks information
* @param snap Web100 snapshot structure
*/
void findCwndPeaks(tcp_stat_agent* agent, CwndPeaks* peaks,
tcp_stat_snap* snap) {
int CurCwnd;
#if USE_WEB100
web100_group* group;
web100_var* var;
char tmpstr[256];
#elif USE_WEB10G
struct estats_val value;
#endif
#if USE_WEB100
web100_agent_find_var_and_group(agent, "CurCwnd", &group, &var);
web100_snap_read(var, snap, tmpstr);
CurCwnd = atoi(web100_value_to_text(web100_get_var_type(var), tmpstr));
#elif USE_WEB10G
web10g_find_val(snap, "CurCwnd", &value);
CurCwnd = value.uv32;
#endif
if (slowStart) {
if (CurCwnd < prevCWNDval) {
slowStart = 0;
peaks->max = prevCWNDval;
peaks->amount = 1;
decreasing = 1;
}
} else {
// current congestion window < previous value, so, decreasing
if (CurCwnd < prevCWNDval) {
// update values based on actual values
if (prevCWNDval > peaks->max) {
peaks->max = prevCWNDval;
}
if (!decreasing) {
peaks->amount += 1;
}
decreasing = 1;
// current congestion window size > previous value,
} else if (CurCwnd > prevCWNDval) {
// not decreasing.
if ((peaks->min == -1) || (prevCWNDval < peaks->min)) {
peaks->min = prevCWNDval;
}
decreasing = 0;
}
}
prevCWNDval = CurCwnd;
}