Resize progress bar when terminal size changes (fixes github #159)

include/dwarfs/cached_value.h

@@ -0,0 +1,50 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/**
+ * \author     Marcus Holland-Moritz ([email protected])
+ * \copyright  Copyright (c) Marcus Holland-Moritz
+ *
+ * This file is part of dwarfs.
+ *
+ * dwarfs is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * dwarfs is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <functional>
+#include <variant>
+
+namespace dwarfs {
+
+template <typename T>
+class cached_value {
+ public:
+  using function_type = std::function<T()>;
+
+  cached_value(function_type f)
+      : v_{f} {}
+
+  T const& get() {
+    if (std::holds_alternative<function_type>(v_)) [[unlikely]] {
+      v_ = std::get<function_type>(v_)();
+    }
+    return std::get<T>(v_);
+  }
+
+  T const& operator()() { return get(); }
+
+ private:
+  std::variant<function_type, T> v_;
+};
+
+} // namespace dwarfs

include/dwarfs/console_writer.h

@@ -23,6 +23,7 @@
 
 #include <atomic>
 #include <cstddef>
+#include <functional>
 #include <iosfwd>
 #include <mutex>
 #include <string>
@@ -36,12 +37,14 @@ class progress;
 
 class console_writer : public logger {
  public:
+  using get_term_width_type = std::function<size_t()>;
+
   enum display_mode { NORMAL, REWRITE };
   enum progress_mode { NONE, SIMPLE, ASCII, UNICODE };
 
-  console_writer(std::ostream& os, progress_mode pg_mode, size_t width,
-                 level_type threshold, display_mode mode = NORMAL,
-                 bool verbose = false);
+  console_writer(std::ostream& os, progress_mode pg_mode,
+                 get_term_width_type get_term_width, level_type threshold,
+                 display_mode mode = NORMAL, bool verbose = false);
 
   void write(level_type level, const std::string& output, char const* file,
              int line) override;
@@ -58,7 +61,7 @@ class console_writer : public logger {
   double frac_;
   std::atomic<size_t> counter_{0};
   progress_mode const pg_mode_;
-  size_t const width_;
+  get_term_width_type get_term_width_;
   display_mode const mode_;
   bool const color_;
   bool const with_context_;

src/dwarfs/console_writer.cpp

@@ -27,6 +27,7 @@
 
 #include <fmt/format.h>
 
+#include "dwarfs/cached_value.h"
 #include "dwarfs/console_writer.h"
 #include "dwarfs/entry.h"
 #include "dwarfs/entry_interface.h"
@@ -78,13 +79,14 @@ std::string progress_bar(size_t width, double frac, bool unicode) {
 } // namespace
 
 console_writer::console_writer(std::ostream& os, progress_mode pg_mode,
-                               size_t width, level_type threshold,
-                               display_mode mode, bool with_context)
+                               get_term_width_type get_term_width,
+                               level_type threshold, display_mode mode,
+                               bool with_context)
     : os_(os)
     , threshold_(threshold)
     , frac_(0.0)
     , pg_mode_(pg_mode)
-    , width_(width)
+    , get_term_width_(get_term_width)
     , mode_(mode)
     , color_(stream_is_fancy_terminal(os))
     , with_context_(with_context)
@@ -180,12 +182,13 @@ void console_writer::update(const progress& p, bool last) {
   const char* newline = pg_mode_ != NONE ? "\x1b[K\n" : "\n";
 
   std::ostringstream oss;
+  cached_value width(get_term_width_);
 
   bool fancy = pg_mode_ == ASCII || pg_mode_ == UNICODE;
 
   if (last || fancy) {
     if (fancy) {
-      for (size_t i = 0; i < width_; ++i) {
+      for (size_t i = 0; i < width.get(); ++i) {
         oss << (pg_mode_ == UNICODE ? "⎯" : "-");
       }
       oss << "\n";
@@ -205,7 +208,8 @@ void console_writer::update(const progress& p, bool last) {
       }
 
       if (fancy) {
-        oss << terminal_colored(p.status(width_), termcolor::BOLD_CYAN, color_)
+        oss << terminal_colored(p.status(width.get()), termcolor::BOLD_CYAN,
+                                color_)
             << newline;
       }
 
@@ -305,7 +309,7 @@ void console_writer::update(const progress& p, bool last) {
       os_ << oss.str();
     }
   } else {
-    oss << progress_bar(width_ - 6, frac_, pg_mode_ == UNICODE)
+    oss << progress_bar(width.get() - 6, frac_, pg_mode_ == UNICODE)
         << fmt::format("{:3.0f}% ", 100 * frac_) << "-\\|/"[counter_ % 4]
         << '\n';
 

src/mkdwarfs_main.cpp

@@ -868,7 +868,7 @@ int mkdwarfs_main(int argc, sys_char** argv) {
   auto pg_mode = DWARFS_NOTHROW(progress_modes.at(progress_mode));
   auto log_level = logger::parse_level(log_level_str);
 
-  console_writer lgr(std::cerr, pg_mode, get_term_width(), log_level,
+  console_writer lgr(std::cerr, pg_mode, get_term_width, log_level,
                      recompress ? console_writer::REWRITE
                                 : console_writer::NORMAL,
                      log_level >= logger::DEBUG);