Ptrace cache

how_to/nob.c

@@ -10,6 +10,7 @@ const char *examples[] = {
     "001_basic_usage",
     "005_parallel_build",
     "010_nob_two_stage",
+    "ptrace_cache",
 };
 
 int main(int argc, char **argv)

how_to/ptrace_cache/.gitignore

@@ -0,0 +1,3 @@
+nob
+nob.old
+build/

how_to/ptrace_cache/nob.c

@@ -0,0 +1,97 @@
+#define NOB_IMPLEMENTATION
+#include "nob.h"
+
+// Just for debugging and to see what is cached in human readable format
+static void nob__ptrace_cache_print_makefile(Nob_Ptrace_Cache cache);
+static void nob__ptrace_cache_print_debug(Nob_Ptrace_Cache cache);
+
+int main(int argc, char **argv)
+{
+    NOB_GO_REBUILD_URSELF_PLUS(argc, argv, "nob.h");
+    if (!nob_mkdir_if_not_exists("build")) return 1;
+
+    Nob_Cmd cmd = {0};
+    // Cache data will be read and written to a .file_path field ("build/nob.cache" in this case.)
+    // In case .file_path field is not set, cache data will only be in memory.
+    Nob_Ptrace_Cache cache = { .file_path = "build/nob.cache" };
+
+    for (int i = 0; i < 10; ++i) {
+        nob_cc(&cmd);
+        nob_cc_flags(&cmd);
+        nob_cc_output(&cmd, "build/foo");
+        nob_cc_inputs(&cmd, "src/foo.c");
+        if (!nob_cmd_run(&cmd, .ptrace_cache = &cache)) return 1;
+
+        // Don't cache this command.
+        nob_cmd_append(&cmd, "./build/foo");
+        if (!nob_cmd_run(&cmd)) return 1;
+    }
+
+    // Convert Nob_Ptrace_Cache to Makefile and print it
+    nob__ptrace_cache_print_makefile(cache);
+    nob__ptrace_cache_print_debug(cache);
+
+    // Save cache data to disc.
+    // And free all memory malloced by ptrace_cache.
+    nob_ptrace_cache_finish(cache);
+
+    nob_cmd_free(cmd);
+
+    return 0;
+}
+
+#if NOB_HAS_PTRACE_CACHE
+static void nob__ptrace_cache_print_makefile_rec(Nob_Ptrace_Cache cache, Nob_String_Builder* cur_command, int parent)
+{
+    size_t old_count = cur_command->count;
+    for (size_t i = 0; i < cache.nodes.count; ++i) {
+        Nob__Ptrace_Cache_Node node = cache.nodes.items[i];
+        if (node.parent != parent) continue;
+        if (node.kind == Nob__Ptrace_Cache_Node_Arg) nob_sb_append_cstr(cur_command, " ");
+        if (node.kind == Nob__Ptrace_Cache_Node_Stdin) nob_sb_append_cstr(cur_command, " < ");
+        if (node.kind == Nob__Ptrace_Cache_Node_Stdout) nob_sb_append_cstr(cur_command, " > ");
+        if (node.kind == Nob__Ptrace_Cache_Node_Stderr) nob_sb_append_cstr(cur_command, " 2> ");
+        nob_sb_append_cstr(cur_command, &cache.arena.items[node.arg_index]);
+        if (node.input_paths.count != 0 || node.output_paths.count != 0) {
+            for (size_t j = 0; j < node.output_paths.count;) {
+                printf("%s", &cache.arena.items[node.output_paths.items[j]]);
+                if (++j < node.output_paths.count) printf(" "); 
+            }
+            printf(": ");
+            for (size_t j = 0; j < node.input_paths.count; ++j) printf("%s ", &cache.arena.items[node.input_paths.items[j]]);
+            printf("\n\t");
+            printf("%.*s\n\n", (int)cur_command->count, cur_command->items);
+        }
+        nob__ptrace_cache_print_makefile_rec(cache, cur_command, (int)i);
+        cur_command->count = old_count;
+    }
+}
+
+static void nob__ptrace_cache_print_makefile(Nob_Ptrace_Cache cache)
+{
+    Nob_String_Builder cur_command = { 0 };
+    nob__ptrace_cache_print_makefile_rec(cache, &cur_command, -1);
+    nob_sb_free(cur_command);
+}
+
+static void nob__ptrace_cache_print_debug(Nob_Ptrace_Cache cache)
+{
+    printf("-----\n");
+    for (size_t i = 0; i < cache.nodes.count; ++i) {
+        Nob__Ptrace_Cache_Node node = cache.nodes.items[i];
+        printf("[%zu]%s(parent=%d, kind=%d, in_c=%zu, out_c=%zu)\n", i, &cache.arena.items[node.arg_index], node.parent, node.kind, node.input_paths.count, node.output_paths.count);
+    }
+    printf("-----\n");
+}
+
+#else
+static void nob__ptrace_cache_print_makefile(Nob_Ptrace_Cache cache)
+{
+    printf("Ptrace not implmented on this platform\n");
+}
+
+static void nob__ptrace_cache_print_debug(Nob_Ptrace_Cache cache)
+{
+    printf("Ptrace not implmented on this platform\n");
+}
+#endif // NOB_HAS_PTRACE_CACHE

how_to/ptrace_cache/nob.h

@@ -0,0 +1 @@
+../../nob.h

how_to/ptrace_cache/src/foo.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main(void)
+{
+    printf("Foo, bar\n");
+    return 0;
+}