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MJL 21/11/06 Applied transfer size limitation in AnstoHttpGetHistogram code; see comments re AppWeb HTTP 1.1 chunking

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r1313 | mle | 2006-11-22 12:56:56 +1100 (Wed, 22 Nov 2006) | 2 lines
This commit is contained in:
Mark Lesha
2006-11-22 12:56:56 +11:00
committed by Douglas Clowes
parent 85d41577b3
commit fc9c909c84
1 changed files with 69 additions and 24 deletions
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93
site_ansto/anstohttp.c
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@@ -554,32 +554,77 @@ static int AnstoHttpGetHistogram(pHistDriver self, SConnection *pCon,
pAnstoHttp pPriv = NULL;
int status, len, i;
pPriv = (pAnstoHttp)self->pPriv;
assert(pPriv != NULL);
// For the ANSTO Histogram Server, the transfer size may be large
// and this can lead to transmission of the data from the server in chunks.
// This is apparent from the presence of 'xxxxx; chunk length nnnnnn' in the
// data when the transfer size is greater than 128K.
// e.g. a request for 64K elements is split into two chunks,
// and each has the header '20000; chunk length 131072'.
// However for some reason ghttp_get_body_len returns only the data size,
// even though there are header(s) added to the data.
// So, for the time being we play it safe and divide the transfer
// into chunks of less than 128KB.
//
// MJL 22/11/06: Found that AppWeb 2.1.0 supports HTTP 1.1 chunking,
// but this can be turned off by specifying HttpChunking off in the AppWeb
// config file, which is what we do currently, so the transfer size limitation code below
// is no longer needed. I've left it in with a much larger size restriction,
// just in case it's required later on for any reason (to improve transfer reliability?).
// Apparently the AppWeb 2.1.0 HTTP chunking feature is broken, because when the
// data is opened directly from the web server using an editor like KHexEdit, the open
// stalls for large data sizes unless chunking is disabled. This shows it is
// an AppWeb problem, not a ghttp problem.
// For AppWeb versions before 2.1.0, HTTP chunking is not available anyway.
snprintf(command,255,"%s?bank=%d&start=%d&end=%d",gethm,bank,
start,end);
pPriv = (pAnstoHttp)self->pPriv;
assert(pPriv != NULL);
status = anstoHttpGet(pPriv,command);
if(status != 1){
return HWFault;
}
len = ghttp_get_body_len(pPriv->syncRequest);
if(len < (end-start)*sizeof(int)){
pPriv->errorCode = BODYSHORT;
strncpy(pPriv->hmError,"Not enough data received from HM",511);
return HWFault;
}
hmdata = (HistInt *)ghttp_get_body(pPriv->syncRequest);
if(hmdata == NULL){ // MJL check ghttp_get_body for NULL return
pPriv->errorCode = NOBODY;
strncpy(pPriv->hmError,"No body in HM data response",511);
return HWFault;
}
for(i = 0; i < (end - start); i++){
data[i] = ntohl(hmdata[i]);
}
// How this limit is set in the server is not obvious... anyway, it should not change.
// MJL 22/11/06: Turned HTTP 1.1 chunking off at the histogram server, so we no longer
// need a size restriction. Leave the code in just in case it's needed for other reasons,
// but set a larger maximum request size.
//#define MAX_HTTP_REQUEST_BYTES 131072
#define MAX_HTTP_REQUEST_BYTES 1048576
// Do the HTTP data transfer in bite sized pieces
while(end>start)
{
int size=((end-start)>(MAX_HTTP_REQUEST_BYTES/sizeof(int)))
?(MAX_HTTP_REQUEST_BYTES/sizeof(int)):(end-start);
snprintf(command,255,"%s?bank=%d&start=%d&end=%d",gethm,bank,
start,start+size);
status = anstoHttpGet(pPriv,command);
if(status != 1){
return HWFault;
}
len = ghttp_get_body_len(pPriv->syncRequest);
if(len < size*sizeof(int)){
pPriv->errorCode = BODYSHORT;
strncpy(pPriv->hmError,"Not enough data received from HM",511);
return HWFault;
}
hmdata = (HistInt *)ghttp_get_body(pPriv->syncRequest);
if(hmdata == NULL){ // MJL check ghttp_get_body for NULL return
pPriv->errorCode = NOBODY;
strncpy(pPriv->hmError,"No body in HM data response",511);
return HWFault;
}
// MJL removed the ntohl, our histogram server doesn't apply htonl,
// so the data arrives in LE format. (Would have to buffer data
// at the server otherwise...)
// Doubt this will raise any conpatibility issues.
for(i = 0; i < size; i++){
//data[i] = ntohl(hmdata[i]);
data[i] = hmdata[i];
}
data+=size;
start+=size;
}
return OKOK;
}
/*--------------------------------------------------------------------*/