102 lines
2.5 KiB
Markdown
102 lines
2.5 KiB
Markdown
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```c title="C"
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#include <kreuzberg.h>
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#include <stdatomic.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/* Shared state lives in `user_data` and is forwarded to every vtable callback.
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* Use atomics or a mutex if more than one thread can call into the plugin. */
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typedef struct {
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atomic_size_t call_count;
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} StatefulState;
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static char *dup_cstr(const char *s) {
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size_t len = strlen(s);
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char *out = (char *)malloc(len + 1);
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if (out) {
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memcpy(out, s, len + 1);
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}
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return out;
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}
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static int32_t initialize_fn(const void *user_data, char **out_error) {
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(void)out_error;
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StatefulState *state = (StatefulState *)user_data;
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atomic_store(&state->call_count, 0);
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return 0;
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}
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static int32_t shutdown_fn(const void *user_data, char **out_error) {
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(void)out_error;
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const StatefulState *state = (const StatefulState *)user_data;
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size_t count = atomic_load(&state->call_count);
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fprintf(stderr, "stateful-plugin: shutdown after %zu calls\n", count);
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return 0;
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}
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static int32_t process_fn(
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const void *user_data,
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const char *result,
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const char *config,
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char **out_error
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) {
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(void)result;
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(void)config;
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(void)out_error;
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StatefulState *state = (StatefulState *)user_data;
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atomic_fetch_add(&state->call_count, 1);
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return 0;
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}
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static int32_t processing_stage_fn(const void *user_data, char **out_result) {
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(void)user_data;
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*out_result = dup_cstr("\"Middle\"");
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return 0;
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}
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static int32_t priority_fn(const void *user_data) {
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(void)user_data;
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return 50;
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}
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static void free_user_data(void *user_data) {
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free(user_data);
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}
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int main(void) {
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StatefulState *state = (StatefulState *)malloc(sizeof(StatefulState));
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if (!state) {
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return 1;
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}
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atomic_init(&state->call_count, 0);
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KREUZBERGKreuzbergPostProcessorVTable vtable = {0};
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vtable.initialize_fn = initialize_fn;
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vtable.shutdown_fn = shutdown_fn;
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vtable.process = process_fn;
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vtable.processing_stage = processing_stage_fn;
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vtable.priority = priority_fn;
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vtable.free_user_data = free_user_data;
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char *err = NULL;
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int32_t rc = kreuzberg_register_post_processor(
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"stateful-plugin",
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vtable,
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state,
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&err
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);
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if (rc != 0) {
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fprintf(stderr, "register post-processor failed: %s\n",
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err ? err : "(no detail)");
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kreuzberg_free_string(err);
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free(state);
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return 1;
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}
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printf("stateful-plugin registered\n");
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return 0;
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}
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```
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