Implement --log-colors with always/never/auto (#15792)

With auto by default

Signed-off-by: Eric Curtin <ericcurtin17@gmail.com>

common/arg.cpp

@@ -1263,6 +1263,18 @@ static std::string list_builtin_chat_templates() {
     return msg.str();
 }
 
+static bool is_truthy(const std::string & value) {
+    return value == "on" || value == "enabled" || value == "1";
+}
+
+static bool is_falsey(const std::string & value) {
+    return value == "off" || value == "disabled" || value == "0";
+}
+
+static bool is_autoy(const std::string & value) {
+    return value == "auto" || value == "-1";
+}
+
 common_params_context common_params_parser_init(common_params & params, llama_example ex, void(*print_usage)(int, char **)) {
     // load dynamic backends
     ggml_backend_load_all();
@@ -1544,21 +1556,21 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
             params.n_chunks = value;
         }
     ).set_examples({LLAMA_EXAMPLE_IMATRIX, LLAMA_EXAMPLE_PERPLEXITY, LLAMA_EXAMPLE_RETRIEVAL}));
-    add_opt(common_arg(
-        {"-fa", "--flash-attn"}, "FA",
-        string_format("set Flash Attention use ('on', 'off', or 'auto', default: '%s')", llama_flash_attn_type_name(params.flash_attn_type)),
-        [](common_params & params, const std::string & value) {
-            if (value == "on" || value == "enabled" || value == "1") {
-                params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_ENABLED;
-            } else if (value == "off" || value == "disabled" || value == "0") {
-                params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_DISABLED;
-            } else if (value == "auto" || value == "-1") {
-                params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_AUTO;
-            } else {
-                throw std::runtime_error(string_format("error: unkown value for --flash-attn: '%s'\n", value.c_str()));
-            }
-        }
-    ).set_env("LLAMA_ARG_FLASH_ATTN"));
+    add_opt(common_arg({ "-fa", "--flash-attn" }, "[on|off|auto]",
+                       string_format("set Flash Attention use ('on', 'off', or 'auto', default: '%s')",
+                                     llama_flash_attn_type_name(params.flash_attn_type)),
+                       [](common_params & params, const std::string & value) {
+                           if (is_truthy(value)) {
+                               params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_ENABLED;
+                           } else if (is_falsey(value)) {
+                               params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_DISABLED;
+                           } else if (is_autoy(value)) {
+                               params.flash_attn_type = LLAMA_FLASH_ATTN_TYPE_AUTO;
+                           } else {
+                               throw std::runtime_error(
+                                   string_format("error: unkown value for --flash-attn: '%s'\n", value.c_str()));
+                           }
+                       }).set_env("LLAMA_ARG_FLASH_ATTN"));
     add_opt(common_arg(
         {"-p", "--prompt"}, "PROMPT",
         "prompt to start generation with; for system message, use -sys",
@@ -3134,13 +3146,21 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
             common_log_set_file(common_log_main(), value.c_str());
         }
     ));
-    add_opt(common_arg(
-        {"--log-colors"},
-        "Enable colored logging",
-        [](common_params &) {
-            common_log_set_colors(common_log_main(), true);
-        }
-    ).set_env("LLAMA_LOG_COLORS"));
+    add_opt(common_arg({ "--log-colors" }, "[on|off|auto]",
+                       "Set colored logging ('on', 'off', or 'auto', default: 'auto')\n"
+                       "'auto' enables colors when output is to a terminal",
+                       [](common_params &, const std::string & value) {
+                           if (is_truthy(value)) {
+                               common_log_set_colors(common_log_main(), LOG_COLORS_ENABLED);
+                           } else if (is_falsey(value)) {
+                               common_log_set_colors(common_log_main(), LOG_COLORS_DISABLED);
+                           } else if (is_autoy(value)) {
+                               common_log_set_colors(common_log_main(), LOG_COLORS_AUTO);
+                           } else {
+                               throw std::invalid_argument(
+                                   string_format("error: unkown value for --log-colors: '%s'\n", value.c_str()));
+                           }
+                       }).set_env("LLAMA_LOG_COLORS"));
     add_opt(common_arg(
         {"-v", "--verbose", "--log-verbose"},
         "Set verbosity level to infinity (i.e. log all messages, useful for debugging)",

common/log.cpp

@@ -4,17 +4,52 @@
 #include <condition_variable>
 #include <cstdarg>
 #include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <mutex>
 #include <sstream>
 #include <thread>
 #include <vector>
 
+#if defined(_WIN32)
+#    include <io.h>
+#    include <windows.h>
+#    define isatty _isatty
+#    define fileno _fileno
+#else
+#    include <unistd.h>
+#endif // defined(_WIN32)
+
 int common_log_verbosity_thold = LOG_DEFAULT_LLAMA;
 
 void common_log_set_verbosity_thold(int verbosity) {
     common_log_verbosity_thold = verbosity;
 }
 
+// Auto-detect if colors should be enabled based on terminal and environment
+static bool common_log_should_use_colors_auto() {
+    // Check NO_COLOR environment variable (https://no-color.org/)
+    if (const char * no_color = std::getenv("NO_COLOR")) {
+        if (no_color[0] != '\0') {
+            return false;
+        }
+    }
+
+    // Check TERM environment variable
+    if (const char * term = std::getenv("TERM")) {
+        if (std::strcmp(term, "dumb") == 0) {
+            return false;
+        }
+    }
+
+    // Check if stdout and stderr are connected to a terminal
+    // We check both because log messages can go to either
+    bool stdout_is_tty = isatty(fileno(stdout));
+    bool stderr_is_tty = isatty(fileno(stderr));
+
+    return stdout_is_tty || stderr_is_tty;
+}
+
 static int64_t t_us() {
     return std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
 }
@@ -353,6 +388,11 @@ struct common_log * common_log_init() {
 
 struct common_log * common_log_main() {
     static struct common_log log;
+    static std::once_flag    init_flag;
+    std::call_once(init_flag, [&]() {
+        // Set default to auto-detect colors
+        log.set_colors(common_log_should_use_colors_auto());
+    });
 
     return &log;
 }
@@ -380,8 +420,19 @@ void common_log_set_file(struct common_log * log, const char * file) {
     log->set_file(file);
 }
 
-void common_log_set_colors(struct common_log * log, bool colors) {
-    log->set_colors(colors);
+void common_log_set_colors(struct common_log * log, log_colors colors) {
+    if (colors == LOG_COLORS_AUTO) {
+        log->set_colors(common_log_should_use_colors_auto());
+        return;
+    }
+
+    if (colors == LOG_COLORS_DISABLED) {
+        log->set_colors(false);
+        return;
+    }
+
+    GGML_ASSERT(colors == LOG_COLORS_ENABLED);
+    log->set_colors(true);
 }
 
 void common_log_set_prefix(struct common_log * log, bool prefix) {

common/log.h

@@ -24,6 +24,12 @@
 #define LOG_DEFAULT_DEBUG 1
 #define LOG_DEFAULT_LLAMA 0
 
+enum log_colors {
+    LOG_COLORS_AUTO     = -1,
+    LOG_COLORS_DISABLED = 0,
+    LOG_COLORS_ENABLED  = 1,
+};
+
 // needed by the LOG_TMPL macro to avoid computing log arguments if the verbosity lower
 // set via common_log_set_verbosity()
 extern int common_log_verbosity_thold;
@@ -65,10 +71,10 @@ void common_log_add(struct common_log * log, enum ggml_log_level level, const ch
 // D - debug   (stderr, V = LOG_DEFAULT_DEBUG)
 //
 
-void common_log_set_file      (struct common_log * log, const char * file);       // not thread-safe
-void common_log_set_colors    (struct common_log * log,       bool   colors);     // not thread-safe
-void common_log_set_prefix    (struct common_log * log,       bool   prefix);     // whether to output prefix to each log
-void common_log_set_timestamps(struct common_log * log,       bool   timestamps); // whether to output timestamps in the prefix
+void common_log_set_file      (struct common_log * log, const char * file); // not thread-safe
+void common_log_set_colors    (struct common_log * log, log_colors colors); // not thread-safe
+void common_log_set_prefix    (struct common_log * log, bool prefix);       // whether to output prefix to each log
+void common_log_set_timestamps(struct common_log * log, bool timestamps);   // whether to output timestamps in the prefix
 
 // helper macros for logging
 // use these to avoid computing log arguments if the verbosity of the log is higher than the threshold