I am using Varnish 4.0.
My backend is adding to some responses an http header "x-count"
I would like to log the value of "x-count" into a file with a line break.
I assumed i should do it in VCL deliver.
Here is what i have so far :
sub vcl_deliver {
if (resp.http.x-count-this:) {
set resp.http.X-infodbg = "xx";
C{
FILE *fp;
fp = fopen("/tmp/test.txt", "w+");
fputs(VRT_GetHdr(sp, HDR_OBJ, "\013x-count-this:"), fp);
fputs("\n", fp);
fclose(fp);
}C
}
}
Of course it doesnt work and there is a couple of errors ..
./vcl.gK2lu7uM.c: In function ‘VGC_function_vcl_deliver’:
./vcl.gK2lu7uM.c:1049:22: error: ‘sp’ undeclared (first use in this
function) ./vcl.gK2lu7uM.c:1049:22: note: each undeclared identifier
is reported only once for each function it appears in
./vcl.gK2lu7uM.c:1049:5: error: passing argument 2 of ‘VRT_GetHdr’
makes pointer from integer without a cast [-Werror]
./vcl.gK2lu7uM.c:330:7: note: expected ‘const struct gethdr_s *’ but
argument is of type ‘int’ ./vcl.gK2lu7uM.c:1049:5: error: too many
arguments to function ‘VRT_GetHdr’ ./vcl.gK2lu7uM.c:330:7: note:
declared here
I have to say that i simply copy/pasted "sp" from some examples, but i have no idea where it comes from (i suppose the inline C was in a different context and therefore it was declared there but not in vcl_deliver)
So the probably undocumented differences between Varnish 4 and 3 in the above examples are :
VRT_GetHdr is now VRT_GetHdr(context, struct gethdr_s)
sp doesn't exist, but there is a "ctx" variable
Found this, there :
http://jan.bogutzki.de/Artikel/395/set-ttl-in-varnish-4.html
char *stuffid;
const struct gethdr_s hdr = { HDR_BERESP, "\015x-count-this:" };
stuffid = VRT_GetHdr(ctx, &hdr);
And now a different story: Varnish is crashing as soon as the backend sends back "count-this", but that is a different problem :p (my crappy C code probably)
I don't have Varnish 4.0 handy to test this out, but I was able to get your example working with Varnish 3.0. When I tried the VCL as is, I wasn't getting the exact error you are though. The first change:
if (resp.http.x-count-this:) {
needs to be:
if (resp.http.x-count-this) {
The colon should be left off of the header name when referred to this way. Next:
fputs(VRT_GetHdr(sp, HDR_OBJ, "\013x-count-this:"), fp);
needs to be:
fputs(VRT_GetHdr(sp, HDR_OBJ, "\015x-count-this:"), fp);
The length value in that string needs to be in octal for some reason, and 13 in octal is 15. Making those changes got this to work for me. That being said, you many want to look into using open and fcntl instead of fopen since without file locking I'm not sure what the effect of multiple requests contending for that file would be.
Related
I am getting a strange set of error in my Visual Studio 2010 compiler.
I am getting the errors of
error C2572: redefinition of default parameter
error C2011: 'class' type redefinition
I have checked thoroughly and I know very well that in the function definition, I have not given the default parameter values and I have given default parameter value only in function prototype in the header file.
Also, I am very much sure that no two class has been given the same class name.
Please can anybody tell me what could be the other reasons for getting these set of errors?
I have not got the exact reason why it was happening, but I have overcome it by using some simple techniques.
I used function overloading concept to avoid default parameter list. It will cause in duplication of code, but it has proved to be very effective.
So something like this
void myFunction( int, char * = '\0', char * = '\0' );
would become something like this
void myFunction( int );
void myFunction( int, char * );
void myFunction( int, char *, char * );
In this example, code is getting duplicated two times but it seems to be only work around solution.
Next, for the strange class type redefinition error, I was instantiating the class variable in many files. So, I removed that feature of instantiation everywhere and went with global variable something like this.
File named as myHeader.h
#include "myFile.h"
myClass myObj;
And in all the other files
#include "myHeader.h"
myObj.function1( );
myObj.function2( );
I dig up an old project and wanted to compile it, but received several errors, a few of those being a c2664:
error C2664: 'std::make_pair' : cannot convert parameter 1 from 'CUser *' to 'CUser *&&'
error C2664: 'std::make_pair' : cannot convert parameter 1 from 'unsigned long' to ' unsigned long &&'
The relevant code parts are:
//typedef for the userdata map
typedef std::map<unsigned long, std::pair<CUser*,userstatus*>> UserDataMapType;
//...
Inc::incret CUserManager::AddUser(unsigned long ID, CUser* pUser, userstatus* pUserStatus)
{
//...
std::pair<UserDataMapType::iterator, bool> ret = m_mapUserData.insert(std::make_pair<unsigned long, std::pair<CUser*, userstatus*>>(ID, std::make_pair<CUser*, userstatus*>(pUser, pUserStatus)));
//...
}
I tried to make the function parameters const, but that did not help.
It did compile just fine in VS2010.
Please help me find what causes this and how to solve it.
make_pair() has been changed in VS2012 to support a new C++11 feature called move semantics and I suspect that explicitly specifying the types for make_pair() is getting in the way.
Remember that make_pair() does not need any template parameters to be explicitly specified. It deduces them from the type of each argument.
Try removing the explicit template arguments from both calls to make_pair() like so...
std::pair<UserDataMapType::iterator, bool> ret = m_mapUserData.insert(std::make_pair(ID, std::make_pair(pUser, pUserStatus)));
Explicitly providing them like this would have worked fine pre-VS2012 because of a new C++11 feature added called move semantics. You'll want to read up on that subject later since you have a shiny new compiler that supports it.
i have a trouble with a function template implementation in a .inl file (visual c++)
I have this on a header file.
math.h ->>
#ifndef _MATH_H
#define _MATH_H
#include <math.h>
template<class REAL=float>
struct Math
{
// inside this structure , there are a lot of functions , for example this..
static REAL sin ( REAL __x );
static REAL abs ( REAL __x );
};
#include "implementation.inl" // include inl file
#endif
and this is the .inl file.
implementation.inl -->>
template<class REAL>
REAL Math<REAL>::sin (REAL __x)
{
return (REAL) sin ( (double) __x );
}
template<class REAL>
REAL Math<REAL>::abs(REAL __x)
{
if( __x < (REAL) 0 )
return - __x;
return __x;
}
the sine function throw me an error at run time when i call it. However , abs function works
correctly.
i think the trouble is the call to one of the functions of the header math.h inside the .inl files
why I can´t use math.h functions inside .inl file ?
The problem has nothing to do with .inl files - you're simply calling Math<REAL>::sin() recursively until the stack overflows. In MSVC 10 I even get a nice warning pointing that out:
warning C4717: 'Math<double>::sin' : recursive on all control paths, function will cause runtime stack overflow
Try:
return (REAL) ::sin ( (double) __x ); // note the `::` operator
Also, as a side note: the macro name _MATH_H is reserved for use by the compiler implementation. In many cases of using an implementation-reserved identifier you'd be somewhat unlucky to actually run into a conflict (though you should still avoid such names). However, in this case that name has a rather high chance of conflicting with the one that math.h might actually be using to prevent itself from being included multiple times.
You should definitely choose a different name that's unlikely to conflict. See What are the rules about using an underscore in a C++ identifier? for the rules.
I've made a variant type to use instead of boost::variant. Mine works storing an index of the current type on a list of the possible types, and storing data in a byte array with enough space to store the biggest type.
unsigned char data[my_types::max_size];
int type;
Now, when I write a value to this variant type comes the trouble. I use the following:
template<typename T>
void set(T a) {
int t = type_index(T);
if (t != -1) {
type = t;
puts("writing atom data");
*((T *) data) = a; //THIS PART CRASHES!!!!
puts("did it!");
} else {
throw atom_bad_assignment;
}
}
The line that crashes is the one that stores data to the internal buffer. As you can see, I just cast the byte array directly to a pointer of the desired type. This gives me bad address signals and bus errors when trying to write some values.
I'm using GCC on a 64-bit system. How do I set the alignment for the byte array to make sure the address of the array is 64-bit aligned? (or properly aligned for any architecture I might port this project to).
EDIT: Thank you all, but the mistake was somewhere else. Apparently, Intel doesn't really care about alignment. Aligned stuff is faster but not mandatory, and the program works fine this way. My problem was I didn't clear the data buffer before writing stuff and this caused trouble with the constructors of some types. I will not, however, mark the question as answered, so more people can give me tips on alignment ;)
See http://gcc.gnu.org/onlinedocs/gcc-4.0.4/gcc/Variable-Attributes.html
unsigned char data[my_types::max_size] __attribute__ ((aligned));
int type;
I believe
#pragma pack(64)
will work on all modern compilers; it definitely works on GCC.
A more correct solution (that doesn't mess with packing globally) would be:
#pragma pack(push, 64)
// define union here
#pragma pack(pop)
I am implementing a smart pointer class using generics and I wanted to force users of this class to properly construct the smart pointer using syntax such as
MyReference<TestCls>(mytest3))
or
MyReference<TestCls> mytest4(new TestCls());
so I have used the explicit keyword on the CTOR, to prevent this:
MyReference aRef = NULL;
However due to unfortunate circumstances beyond my control, I am working on code that is compiled using the ancient MSVC++ 4.1 compiler. I get the following errors when I include the explicit keyword:
MyReference.h(49) : error C2501: 'explicit' : missing decl-specifiers
MyReference.h(51) : error C2143: syntax error : missing ';' before ''
MyReference.h(52) : error C2238: unexpected token(s) preceding ':'
MyReference.h(52) : error C2059: syntax error : 'int constant'
When I add a #define explicit those errors disappear.
This was a hack on my part, just to get the compiler to ignore the keyword. I'm guessing that this means that explicit is not supported by yon olde compiler.
Can someone confirm this and is there anyone out there with knowledge of a workaround solution for this?
Merci Beaucoups,
Dennis.
This site has a workaround for this, namely:
Unfortunately, older compilers may not
support the use of "explicit", which
could be a headache. If you're stuck
working with an out-of-date compiler
and can't get one that has better
support for the C++ standard, your
best solution may be to take advantage
of the fact that only a single
implicit conversion will take place
for a given value. You can exploit
this by using an intermediate class
that implicitly creates an object of
each type, and then have your main
class implicitly create objects from
that class:
class proxy
{
public:
proxy(int x) : x(x) {} ;
getValue() { return x; }
private:
int x;
};
class String
{
// this will be equivalent of explicit
String(proxy x) { /* create a string using x.getValue(); */ }
}