Multithreaded ncls (#1232)

Thread out ncls to perform the media decode in different threads, in parallel. Only the display needs be locked. On a directory of 200 files on my 39070X, this speeds ncls from ~5s to ~1s. On 75 files, we go from ~.5s to ~.2s. On a single file, we lose about 5%. To facilitate this, ncdirect_render_image() has been split into two helpers, ncdirect_render_frame() and ncdirect_raster_frame().

include/ncpp/Direct.hh

@@ -143,6 +143,16 @@ namespace ncpp
 			return ncdirect_render_image (direct, file, align, blitter, scale);
 		}
 
+		struct ncplane* prep_image (const char* file, ncblitter_e blitter, ncscale_e scale) const noexcept
+		{
+			return ncdirect_render_frame (direct, file, blitter, scale);
+		}
+
+		int raster_image (struct ncplane* faken, ncalign_e align, ncblitter_e blitter, ncscale_e scale) const noexcept
+		{
+			return ncdirect_raster_frame (direct, faken, align, blitter, scale);
+		}
+
 		bool putstr (uint64_t channels, const char* utf8) const NOEXCEPT_MAYBE
 		{
 			return error_guard (ncdirect_putstr (direct, channels, utf8), -1);

include/notcurses/direct.h

@@ -7,6 +7,8 @@
 extern "C" {
 #endif
 
+typedef struct ncplane ncdirectv;
+
 #define API __attribute__((visibility("default")))
 
 // ncdirect_init() will call setlocale() to inspect the current locale. If
@@ -109,7 +111,8 @@ API int ncdirect_cursor_pop(struct ncdirect* n);
 
 // Display an image using the specified blitter and scaling. The image may
 // be arbitrarily many rows -- the output will scroll -- but will only occupy
-// the column of the cursor, and those to the right.
+// the column of the cursor, and those to the right. The render/raster process
+// can be split by using ncdirect_render_frame() and ncdirect_raster_frame().
 API int ncdirect_render_image(struct ncdirect* n, const char* filename,
                               ncalign_e align, ncblitter_e blitter,
                               ncscale_e scale);
@@ -189,6 +192,20 @@ ncdirect_getc_blocking(struct ncdirect* n, ncinput* ni){
 // Release 'nc' and any associated resources. 0 on success, non-0 on failure.
 API int ncdirect_stop(struct ncdirect* nc);
 
+// Render an image using the specified blitter and scaling, but do not write
+// the result. The image may be arbitrarily many rows -- the output will scroll
+// -- but will only occupy the column of the cursor, and those to the right.
+// To actually write (and free) this, invoke ncdirect_raster_frame().
+API ncdirectv* ncdirect_render_frame(struct ncdirect* n, const char* filename,
+                                     ncblitter_e blitter, ncscale_e scale);
+
+// Takes the result of ncdirect_render_frame() and writes it to the output. The
+// 'align', 'blitter', and 'scale' arguments must be the same as those passed
+// to ncdirect_render_frame().
+API int ncdirect_raster_frame(struct ncdirect* n, ncdirectv* faken,
+                              ncalign_e align, ncblitter_e blitter,
+                              ncscale_e scale);
+
 #undef API
 
 #ifdef __cplusplus

src/lib/direct.cpp

@@ -425,23 +425,42 @@ ncdirect_dump_plane(ncdirect* n, const ncplane* np, int xoff){
   return 0;
 }
 
-int ncdirect_render_image(ncdirect* n, const char* file, ncalign_e align,
+int ncdirect_raster_frame(ncdirect* n, ncdirectv* faken, ncalign_e align,
                           ncblitter_e blitter, ncscale_e scale){
+  auto bset = rgba_blitter_low(n->utf8, scale, true, blitter);
+  if(!bset){
+    free_plane(faken);
+    return -1;
+  }
+  int lenx = ncplane_dim_x(faken);
+  int xoff = ncdirect_align(n, align, lenx / encoding_x_scale(bset));
+  if(ncdirect_dump_plane(n, faken, xoff)){
+    free_plane(faken);
+    return -1;
+  }
+  int r = ncdirect_flush(n);
+  free_plane(faken);
+  return r;
+}
+
+ncdirectv* ncdirect_render_frame(ncdirect* n, const char* file,
+                                 ncblitter_e blitter, ncscale_e scale){
   struct ncvisual* ncv = ncvisual_from_file(file);
   if(ncv == nullptr){
-    return -1;
+    return nullptr;
   }
 //fprintf(stderr, "OUR DATA: %p rows/cols: %d/%d\n", ncv->data, ncv->rows, ncv->cols);
   int leny = ncv->rows; // we allow it to freely scroll
   int lenx = ncv->cols;
   if(leny == 0 || lenx == 0){
     ncvisual_destroy(ncv);
-    return -1;
+    return nullptr;
   }
 //fprintf(stderr, "render %d/%d to %d+%dx%d scaling: %d\n", ncv->rows, ncv->cols, leny, lenx, scale);
   auto bset = rgba_blitter_low(n->utf8, scale, true, blitter);
   if(!bset){
-    return -1;
+    ncvisual_destroy(ncv);
+    return nullptr;
   }
   int disprows, dispcols;
   if(scale != NCSCALE_NONE){
@@ -469,22 +488,26 @@ int ncdirect_render_image(ncdirect* n, const char* file, ncalign_e align,
   };
   struct ncplane* faken = ncplane_new_internal(nullptr, nullptr, &nopts);
   if(faken == nullptr){
-    return -1;
+    ncvisual_destroy(ncv);
+    return nullptr;
   }
   if(ncvisual_blit(ncv, disprows, dispcols, faken, bset,
                    0, 0, 0, 0, leny, lenx, false)){
     ncvisual_destroy(ncv);
     free_plane(faken);
-    return -1;
+    return nullptr;
   }
   ncvisual_destroy(ncv);
-  int xoff = ncdirect_align(n, align, lenx / encoding_x_scale(bset));
-  if(ncdirect_dump_plane(n, faken, xoff)){
+  return faken;
+}
+
+int ncdirect_render_image(ncdirect* n, const char* file, ncalign_e align,
+                          ncblitter_e blitter, ncscale_e scale){
+  auto faken = ncdirect_render_frame(n, file, blitter, scale);
+  if(!faken){
     return -1;
   }
-  int r = ncdirect_flush(n);
-  free_plane(faken);
-  return r;
+  return ncdirect_raster_frame(n, faken, align, blitter, scale);
 }
 
 int ncdirect_fg_palindex(ncdirect* nc, int pidx){

src/ls/main.cpp

@@ -1,10 +1,15 @@
 #define NCPP_EXCEPTIONS_PLEASE
+#include <queue>
+#include <thread>
+#include <vector>
+#include <atomic>
 #include <cstdlib>
 #include <fcntl.h>
 #include <getopt.h>
 #include <iostream>
 #include <dirent.h>
 #include <unistd.h>
+#include <pthread.h>
 #include <sys/stat.h>
 #include <filesystem>
 #include <sys/types.h>
@@ -13,8 +18,7 @@
 #define AT_NO_AUTOMOUNT 0 // not defined on freebsd
 #endif
 
-static void
-usage(std::ostream& os, const char* name, int code){
+void usage(std::ostream& os, const char* name, int code){
   os << "usage: " << name << " -h | [ -lLR ] [ --align type ] paths...\n";
   os << " -d: list directories themselves, not their contents\n";
   os << " -l: use a long listing format\n";
@@ -26,6 +30,17 @@ usage(std::ostream& os, const char* name, int code){
   exit(code);
 }
 
+struct job {
+  std::filesystem::path dir;
+  std::string p;
+};
+
+static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t outmtx = PTHREAD_MUTEX_INITIALIZER; // guards standard out
+static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+std::queue<job> work;  // jobs available for workers
+bool keep_working;     // set false when we're done so threads die
+
 // context as configured on the command line
 struct lsContext {
   ncpp::Direct nc;
@@ -36,24 +51,23 @@ struct lsContext {
   ncalign_e alignment;
 };
 
-static int
-handle_path(int dirfd, std::filesystem::path& dir, const char* p, const lsContext& ctx, bool toplevel);
+int handle_path(int dirfd, std::filesystem::path& dir, const char* p, const lsContext& ctx, bool toplevel);
 
 // handle a single inode of arbitrary type
-static int
-handle_inode(std::filesystem::path& dir, const char* p, const struct stat* st, const lsContext& ctx){
+int handle_inode(std::filesystem::path& dir, const char* p, const struct stat* st, const lsContext& ctx){
   (void)st; // FIXME handle symlink (dereflinks)
-  std::cout << p << '\n';
-  auto s = dir / p;
-  ctx.nc.render_image(s.c_str(), ctx.alignment, NCBLIT_DEFAULT, NCSCALE_SCALE);
+  (void)ctx; // FIXME handle symlink (dereflinks)
+  pthread_mutex_lock(&mtx);
+  work.emplace(job{dir, p});
+  pthread_mutex_unlock(&mtx);
+  pthread_cond_signal(&cond);
   return 0;
 }
 
 // if |directories| is true, only print details of |p|, and return. otherwise,
 // if |recursedirs| or |toplevel| is set, we will recurse, passing false as
 // toplevel (but preserving |recursedirs|).
-static int
-handle_dir(int dirfd, std::filesystem::path& pdir, const char* p, const struct stat* st, const lsContext& ctx, bool toplevel){
+int handle_dir(int dirfd, std::filesystem::path& pdir, const char* p, const struct stat* st, const lsContext& ctx, bool toplevel){
   if(ctx.directories){
     return handle_inode(pdir, p, st, ctx);
   }
@@ -91,8 +105,7 @@ handle_dir(int dirfd, std::filesystem::path& pdir, const char* p, const struct s
   return 0;
 }
 
-static int
-handle_deref(const char* p, const struct stat* st, const lsContext& ctx){
+int handle_deref(const char* p, const struct stat* st, const lsContext& ctx){
   (void)p;
   (void)st;
   (void)ctx; // FIXME dereference and rerun on target
@@ -101,8 +114,7 @@ handle_deref(const char* p, const struct stat* st, const lsContext& ctx){
 
 // handle some path |p|, either absolute or relative to |dirfd|. |toplevel| is
 // true iff the path was directly listed on the command line.
-static int
-handle_path(int dirfd, std::filesystem::path& pdir, const char* p, const lsContext& ctx, bool toplevel){
+int handle_path(int dirfd, std::filesystem::path& pdir, const char* p, const lsContext& ctx, bool toplevel){
   struct stat st;
   if(fstatat(dirfd, p, &st, AT_NO_AUTOMOUNT)){
     std::cerr << "Error running fstatat(" << p << "): " << strerror(errno) << std::endl;
@@ -118,10 +130,35 @@ handle_path(int dirfd, std::filesystem::path& pdir, const char* p, const lsConte
   return handle_inode(pdir, p, &st, ctx);
 }
 
+// return long-term return code
+void ncls_thread(const lsContext* ctx) {
+  while(true){
+    pthread_mutex_lock(&mtx);
+    while(work.empty() && keep_working){
+      pthread_cond_wait(&cond, &mtx);
+    }
+    if(!work.empty()){
+      job j = work.front();
+      work.pop();
+      pthread_mutex_unlock(&mtx);
+      auto s = j.dir / j.p;
+      auto faken = ctx->nc.prep_image(s.c_str(), NCBLIT_DEFAULT, NCSCALE_SCALE);
+      pthread_mutex_lock(&outmtx);
+      std::cout << j.p << '\n';
+      if(faken){
+        ctx->nc.raster_image(faken, ctx->alignment, NCBLIT_DEFAULT, NCSCALE_SCALE);
+      }
+      pthread_mutex_unlock(&outmtx);
+    }else if(!keep_working){
+      pthread_mutex_unlock(&mtx);
+      return;
+    }
+  }
+}
+
 // these are our command line arguments. they're the only paths for which
 // handle_path() gets toplevel == true.
-static int
-list_paths(const char* const * argv, const lsContext& ctx){
+int list_paths(const char* const * argv, const lsContext& ctx){
   int dirfd = open(".", O_DIRECTORY | O_CLOEXEC);
   if(dirfd < 0){
     std::cerr << "Error opening current directory: " << strerror(errno) << std::endl;
@@ -182,15 +219,34 @@ int main(int argc, char* const * argv){
         break;
     }
   }
+  auto procs = std::thread::hardware_concurrency();
+  if(procs <= 0){
+    procs = 4;
+  }
+  if(procs > 8){
+    procs = 8;
+  }
+  std::vector<std::thread> threads;
   lsContext ctx = {
-    .nc = ncpp::Direct(),
-    .longlisting = longlisting,
-    .recursedirs = recursedirs,
-    .directories = directories,
-    .dereflinks = dereflinks,
-    .alignment = alignment,
+    ncpp::Direct(),
+    longlisting,
+    recursedirs,
+    directories,
+    dereflinks,
+    alignment,
   };
+  keep_working = true;
+  for(auto s = 0u ; s < procs ; ++s){
+    threads.emplace_back(std::thread(ncls_thread, &ctx));
+  }
   static const char* const default_args[] = { ".", nullptr };
   list_paths(argv[optind] ? argv + optind : default_args, ctx);
+  keep_working = false;
+  pthread_cond_broadcast(&cond);
+  for(auto &t : threads){
+//std::cerr << "Waiting on thread " << procs << std::endl;
+    t.join();
+    --procs;
+  }
   return EXIT_SUCCESS;
 }