C language scalar function (remote mode)
This example uses the following file name:
func.cCode
The code in this example shows that, with minor changes, this program works in remote mode:
The change is in the main. The required remote AE connection name, gathered from the launcher, is set and then a loop is added around the accept so it is called five times. This code works like a local AE and handles five iterations as a remote AE.
#include <stdio.h>
#include <stdlib.h>
#include "nzaeapis.h"
static int run(NZAE_HANDLE h);
int main(int argc, char * argv[])
{
if (nzaeIsLocal())
{
NzaeInitialization arg;
memset(&arg, 0, sizeof(arg));
arg.ldkVersion = NZAE_LDK_VERSION;
if (nzaeInitialize(&arg))
{
fprintf(stderr, "initialization failed\n");
return -1;
}
run(arg.handle);
nzaeClose(arg.handle);
}
else {
NZAECONPT_HANDLE hConpt = nzaeconptCreate();
if (!hConpt)
{
fprintf(stderr, "error creating connection point\n");
fflush(stderr);
return -1;
}
const char * conPtName = nzaeRemprotGetRemoteName();
if (!conPtName)
{
fprintf(stderr, "error getting connection point name\n");
fflush(stderr);
exit(-1);
}
if (nzaeconptSetName(hConpt, conPtName))
{
fprintf(stderr, "error setting connection point name\n");
fflush(stderr);
nzaeconptClose(hConpt);
return -1;
}
NzaeremprotInitialization args;
memset(&args, 0, sizeof(args));
args.ldkVersion = NZAE_LDK_VERSION;
args.hConpt = hConpt;
if (nzaeRemprotCreateListener(&args))
{
fprintf(stderr, "unable to create listener - %s\n", \
args.errorMessage);
fflush(stderr);
nzaeconptClose(hConpt);
return -1;
}
NZAEREMPROT_HANDLE hRemprot = args.handle;
NzaeApi api;
int i;
for (i = 0; i < 5; i++)
{
if (nzaeRemprotAcceptApi(hRemprot, &api))
{
fprintf(stderr, "unable to accept API - %s\n", \
nzaeRemprotGetLastErrorText(hRemprot));
fflush(stderr);
nzaeconptClose(hConpt);
nzaeRemprotClose(hRemprot);
return -1;
}
if (api.apiType != NZAE_API_FUNCTION)
{
fprintf(stderr, "unexpected API returned\n");
fflush(stderr);
nzaeconptClose(hConpt);
nzaeRemprotClose(hRemprot);
return -1;
}
printf("testcapi: accepted a remote request\n");
fflush(stdout);
run(api.handle.function);
}
nzaeRemprotClose(hRemprot);
nzaeconptClose(hConpt);
}
return 0;
}
static int run(NZAE_HANDLE h)
{
NzaeMetadata metadata;
if (nzaeGetMetadata(h, &metadata))
{
fprintf(stderr, "get metadata failed\n");
return -1;
}
#define CHECK(value) \
{ \
NzaeRcCode rc = value; \
if (rc) \
{ \
const char * format = "%s in %s at %d"; \
fprintf(stderr, format, \
nzaeGetLastErrorText(h), __FILE__, __LINE__); \
nzaeUserError(h, format, \
nzaeGetLastErrorText(h), __FILE__, __LINE__); \
exit(-1); \
} \
}
if (metadata.outputColumnCount != 1 ||
metadata.outputTypes[0] != NZUDSUDX_DOUBLE)
{
nzaeUserError(h, "expecting one output column of type double");
nzaeDone(h);
return -1;
}
if (metadata.inputColumnCount < 1)
{
nzaeUserError(h, "expecting at least one input column");
nzaeDone(h);
return -1;
}
if (metadata.inputTypes[0] != NZUDSUDX_FIXED
&& metadata.inputTypes[0] != NZUDSUDX_VARIABLE)
{
nzaeUserError(h, "first input column expected to be a string type");
nzaeDone(h);
return -1;
}
for (;;)
{
int i;
double result = 0;
NzaeRcCode rc = nzaeGetNext(h);
if (rc == NZAE_RC_END)
{
break;
}
NzudsData * input = NULL;
CHECK(nzaeGetInputColumn(h, 0, &input));
const char * opString;
if (input->isNull)
{
nzaeUserError(h, "first input column may not be null");
nzaeDone(h);
return -1;
}
if (input->type == NZUDSUDX_FIXED)
{
opString = input->data.pFixedString;
} else if (input->type == NZUDSUDX_VARIABLE)
{
opString = input->data.pVariableString;
} else
{
nzaeUserError(h, "first input column expected to be a string type");
nzaeDone(h);
return -1;
}
enum OperatorEnum
{
OP_ADD = 1,
OP_MULT = 2
} op;
if (strcmp(opString, "+") == 0)
{
op = OP_ADD;
} else if (strcmp(opString, "*") == 0)
{
op = OP_MULT;
result = 1;
} else
{
nzaeUserError(h, "unexpected operator %s", opString);
nzaeDone(h);
return -1;
}
for (i = 1; i < metadata.inputColumnCount; i++)
{
CHECK(nzaeGetInputColumn(h, i, &input));
if (input->isNull)
{
continue;
}
switch (op)
{
case OP_ADD:
switch(input->type)
{
case NZUDSUDX_INT8:
result += *input->data.pInt8;
break;
case NZUDSUDX_INT16:
result += *input->data.pInt16;
break;
case NZUDSUDX_INT32:
result += *input->data.pInt32;
break;
case NZUDSUDX_INT64:
result += *input->data.pInt64;
break;
case NZUDSUDX_FLOAT:
result += *input->data.pFloat;
break;
case NZUDSUDX_DOUBLE:
result += *input->data.pDouble;
break;
case NZUDSUDX_NUMERIC32:
case NZUDSUDX_NUMERIC64:
case NZUDSUDX_NUMERIC128:
// unlike Java, C has no native numeric data types
break;
default:
// ignore nonnumeric type
break;
}
break;
case OP_MULT:
switch(input->type)
{
case NZUDSUDX_INT8:
result *= *input->data.pInt8;
break;
case NZUDSUDX_INT16:
result *= *input->data.pInt16;
break;
case NZUDSUDX_INT32:
result *= *input->data.pInt32;
break;
case NZUDSUDX_INT64:
result *= *input->data.pInt64;
break;
case NZUDSUDX_FLOAT:
result *= *input->data.pFloat;
break;
case NZUDSUDX_DOUBLE:
result *= *input->data.pDouble;
break;
case NZUDSUDX_NUMERIC32:
case NZUDSUDX_NUMERIC64:
case NZUDSUDX_NUMERIC128:
// unlike Java, C has no native numeric data types
break;
default:
// ignore non-numeric type
break;
}
break;
default:
nzaeUserError(h, "internal error, unexpected operator");
nzaeDone(h);
return -1;
}
}
CHECK(nzaeSetOutputDouble(h, 0, result));
CHECK(nzaeOutputResult(h));
}
nzaeDone(h);
return 0;
}Compilation
Use the standard compile, as in local mode:
$NZ_EXPORT_DIR/ae/utilities/bin/compile_ae --language system --version 3 \
--template compile func.c --exe applyRegistration
Registration is slightly different. First, run this to register:
$NZ_EXPORT_DIR/ae/utilities/bin/register_ae --language system --version 3 \
--template udf --exe apply --sig "rem_applyop_c(VARARGS)" \
--return "double" --remote --rname testcapiThen run the following. It specifies the code be registered as a remote AE with a remote name of testcapi, which matches the code. In addition, it registers a launcher:
$NZ_EXPORT_DIR/ae/utilities/bin/register_ae --language system --version 3 \
--template udtf --exe apply --sig "rem_applyop_launch(int8)" \
--return "TABLE(aeresult varchar(255))" --remote --rname testcapi --launchWith the exception of the --rname, --exe and the name portion of --sig, all launchers look like the above. In this case it is a UDTF, since that is the interface for all launchers. The value of --rname must match the name in the code.
Running
To run the AE in remote mode, the executable is run as a “server.” In this instance it handles only queries run on the host. Usually, AEs are started on the SPUs as well. Start an instance on the host:
SELECT * FROM TABLE WITH FINAL(rem_applyop_launch(0));
AERESULT
---------------------------------------------------------------------------------
--
tran: 7788 session: 16354 DATA slc: 0 hardware: 0 machine: bdrosendev process:
13117 thread: 13117
(1 row)
Notice that a different syntax is used to invoke the table function style launcher. This is the syntax used to call any UDTF-based AE. Now run the AE:
SELECT rem_applyop_c('+',1,2);
REM_APPLYOP_C
---------------
3
(1 row)
Finally, cause an error:
SELECT rem_applyop_c(1);
ERROR: first input COLUMN expected TO be a string type