Mihaela Mihaljevic
8e1415aa64
scripts/benchmark.sh generates a deterministic corpus, builds PureXML in release and a C driver against the SDK's libxml2, times parse, serialize, and XPath over the same bytes (best-of-N, internal timing, IO excluded), cross-checks the same XPath count on both sides, and prints the comparison. First honest baseline recorded in docs/benchmarks.md: parse ~30x, xpath ~36x, serialize ~5x slower than libxml2 on a 4.2 MB corpus; these are the numbers #139's optimization passes burn down. The SAX stage isolation is blocked on #142 (the public streaming surface is internal, found by this harness).
85 lines
2.6 KiB
C
85 lines
2.6 KiB
C
/* libxml2 side of the PureXML benchmark (scripts/benchmark.sh).
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* Times the same operations the Swift driver times, over the same file,
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* with internal timing so process startup never taints a number.
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* Output: CSV lines "library,operation,bytes,seconds".
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*/
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#include <libxml/parser.h>
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#include <libxml/tree.h>
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#include <libxml/xpath.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/time.h>
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static double now(void) {
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struct timeval tv;
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gettimeofday(&tv, NULL);
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return (double)tv.tv_sec + (double)tv.tv_usec / 1e6;
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}
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int main(int argc, char **argv) {
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if (argc < 3) {
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fprintf(stderr, "usage: bench-libxml2 <file.xml> <iterations>\n");
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return 1;
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}
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const char *path = argv[1];
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int iterations = atoi(argv[2]);
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xmlInitParser();
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/* Read the bytes once so parse timing excludes IO. */
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FILE *f = fopen(path, "rb");
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if (!f) { perror("open"); return 1; }
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fseek(f, 0, SEEK_END);
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long size = ftell(f);
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fseek(f, 0, SEEK_SET);
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char *buffer = malloc((size_t)size);
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fread(buffer, 1, (size_t)size, f);
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fclose(f);
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/* Parse. */
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double best_parse = 1e9;
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xmlDocPtr doc = NULL;
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for (int i = 0; i < iterations; i++) {
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if (doc) xmlFreeDoc(doc);
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double t0 = now();
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doc = xmlReadMemory(buffer, (int)size, path, NULL, XML_PARSE_NONET);
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double dt = now() - t0;
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if (dt < best_parse) best_parse = dt;
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}
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if (!doc) { fprintf(stderr, "parse failed\n"); return 1; }
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printf("libxml2,parse,%ld,%.6f\n", size, best_parse);
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/* Serialize. */
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double best_serialize = 1e9;
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for (int i = 0; i < iterations; i++) {
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xmlChar *out = NULL;
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int outLen = 0;
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double t0 = now();
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xmlDocDumpMemory(doc, &out, &outLen);
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double dt = now() - t0;
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if (dt < best_serialize) best_serialize = dt;
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xmlFree(out);
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}
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printf("libxml2,serialize,%ld,%.6f\n", size, best_serialize);
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/* XPath: count a broad selection. */
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double best_xpath = 1e9;
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long count = 0;
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for (int i = 0; i < iterations; i++) {
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double t0 = now();
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xmlXPathContextPtr ctx = xmlXPathNewContext(doc);
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xmlXPathObjectPtr res = xmlXPathEvalExpression((const xmlChar *)"count(//item[@kind='even'])", ctx);
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count = (long)res->floatval;
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double dt = now() - t0;
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if (dt < best_xpath) best_xpath = dt;
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xmlXPathFreeObject(res);
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xmlXPathFreeContext(ctx);
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}
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printf("libxml2,xpath,%ld,%.6f\n", size, best_xpath);
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fprintf(stderr, "libxml2 xpath count: %ld\n", count);
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xmlFreeDoc(doc);
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xmlCleanupParser();
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free(buffer);
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return 0;
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}
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