feat: add compression worker threads

src/client/client_cli.c

@@ -211,6 +211,13 @@ static int apply_table_option(Config* config, const OptionEntry* entry, const ch
 int parse_args(Config* config, int argc, char* argv[], int* positional_args,
                int* positional_count) {
   for (int i = 1; i < argc; i++) {
+    const char* threads_prefix = "--compress-threads=";
+    if (strncmp(argv[i], threads_prefix, strlen(threads_prefix)) == 0) {
+      if (set_positive_int_option(&config->compression_threads, argv[i] + strlen(threads_prefix),
+                                  "--compress-threads") != 0)
+        return -1;
+      continue;
+    }
     const OptionEntry* entry = find_table_option(argv[i]);
     if (entry) {
       if (entry->kind != OPT_FLAG) {
@@ -361,6 +368,10 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
         log_message(LOG_LEVEL_ERROR, "--compress-level must be between 1 and 22");
         return -1;
       }
+    } else if (opt_is(argv[i], "--compress-threads", NULL) && i + 1 < argc) {
+      if (set_positive_int_option(&config->compression_threads, argv[++i], "--compress-threads") !=
+          0)
+        return -1;
     } else if (argv[i][0] == '-') {
       fprintf(stderr, "Unknown option: %s\n", argv[i]);
       print_usage();

src/client/client_send.c

@@ -235,7 +235,8 @@ static int send_delta(Client* client, File* file, DeltaSignature* sig, Config* c
 
   Data* to_send = delta_data;
   if (config->use_compression) {
-    to_send = data_compress(delta_data, config->compression_level);
+    to_send = data_compress_with_threads(delta_data, config->compression_level,
+                                         config->compression_threads);
     data_destroy(delta_data);
     if (!to_send)
       return send_status(client->file_descriptor, STATUS_NEXT) ? 1 : -1;
@@ -251,13 +252,15 @@ static int send_delta(Client* client, File* file, DeltaSignature* sig, Config* c
   return ok ? 0 : -1;
 }
 
-typedef bool (*file_send_fn)(File*, int, bool, int, bool);
+typedef bool (*file_send_fn)(File*, int, bool, int, int, bool);
 
 // Send a single file directly (non-incremental path).
-static bool send_file_direct(File* file, int fd, bool use_metadata, int compression_level) {
+static bool send_file_direct(File* file, int fd, bool use_metadata, int compression_level,
+                             int compression_threads) {
   if (!send_status(fd, STATUS_NEXT))
     return false;
-  return file_send_single_calls(file, fd, use_metadata, compression_level, true);
+  return file_send_single_calls_with_threads(file, fd, use_metadata, compression_level,
+                                             compression_threads, true);
 }
 
 // Send a single file directly via sendfile (non-incremental path).
@@ -278,7 +281,8 @@ static int send_single_file(Client* client, File* file, Config* config, bool use
       return send_file_direct_sendfile(file, client->file_descriptor, config->use_metadata) ? 0
                                                                                             : -1;
     }
-    return send_file_direct(file, client->file_descriptor, config->use_metadata, compression_level)
+    return send_file_direct(file, client->file_descriptor, config->use_metadata, compression_level,
+                            config->compression_threads)
                ? 0
                : -1;
   }
@@ -310,7 +314,7 @@ static int send_single_file(Client* client, File* file, Config* config, bool use
   }
 
   // Incremental path with single_calls (supports compression and delta)
-  file_send_fn send_fn = (file_send_fn)file_send_single_calls;
+  file_send_fn send_fn = (file_send_fn)file_send_single_calls_with_threads;
   DeltaSignature* sig = NULL;
   int rc = incremental_check(client, file, config, &sig);
   if (rc < 0) {
@@ -338,7 +342,8 @@ static int send_single_file(Client* client, File* file, Config* config, bool use
         return -1;
     }
   }
-  if (!send_fn(file, client->file_descriptor, config->use_metadata, compression_level, false))
+  if (!send_fn(file, client->file_descriptor, config->use_metadata, compression_level,
+               config->compression_threads, false))
     return -1;
   return 0;
 }
@@ -349,7 +354,8 @@ int send_chunk(Client* client, Chunk* chunk, Config* config) {
       return -1;
     Data* data;
     if (config->use_compression) {
-      data = chunk_compress(chunk, config->compression_level, config->use_metadata);
+      data = chunk_compress_with_threads(chunk, config->compression_level, config->use_metadata,
+                                         config->compression_threads);
     } else {
       data = chunk_serialize(chunk, config->use_metadata);
     }

src/client/client_validation.c

@@ -15,6 +15,10 @@ bool validate_config(const Config* config) {
                                  "(chunk serialization)");
     return false;
   }
+  if (config->compression_threads > 0 && !config->use_compression) {
+    log_message(LOG_LEVEL_ERROR, "--compress-threads requires compression (-c or -z)");
+    return false;
+  }
   if (config->transport == TRANSPORT_SSH && config->use_sendfile) {
     log_message(LOG_LEVEL_ERROR, "-f/--sendfile is not supported with SSH transport");
     return false;

src/client/usage.c

@@ -69,6 +69,7 @@ void print_usage(void) {
   printf("  -S, --sparse        Handle sparse files efficiently\n");
   printf("  --inplace           Update files in-place (no temp+rename)\n");
   printf("  --compress-level <n>    Compression level (default: 5)\n");
+  printf("  --compress-threads <n> Compression worker threads (requires zstd threaded support)\n");
   printf("  --help              Show this help\n");
   printf("  -V, --version       Show version\n");
 }