4 files changed, 75 insertions, 33 deletions
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index afcc2ec58543..2d0acca24216 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -1,6 +1,8 @@
 #include "logging.hh"
 #include "util.hh"
 
+#include <atomic>
+
 namespace nix {
 
 Logger * logger = makeDefaultLogger();
@@ -42,12 +44,7 @@ public:
         writeToStderr(prefix + (tty ? fs.s : filterANSIEscapes(fs.s)) + "\n");
     }
 
-    void startActivity(Activity & activity, Verbosity lvl, const FormatOrString & fs) override
-    {
-        log(lvl, fs);
-    }
-
-    void stopActivity(Activity & activity) override
+    void event(const Event & ev) override
     {
     }
 };
@@ -79,4 +76,8 @@ Logger * makeDefaultLogger()
     return new SimpleLogger();
 }
 
+std::atomic<uint64_t> Activity::nextId{(uint64_t) getpid() << 32};
+
+Activity::Activity() : id(nextId++) { };
+
 }
diff --git a/src/libutil/logging.hh b/src/libutil/logging.hh
index a8c69dbd956d..ddfc336fee07 100644
--- a/src/libutil/logging.hh
+++ b/src/libutil/logging.hh
@@ -13,7 +13,64 @@ typedef enum {
     lvlVomit
 } Verbosity;
 
-class Activity;
+class Activity
+{
+    static std::atomic<uint64_t> nextId;
+public:
+    typedef uint64_t t;
+    const t id;
+    Activity();
+    Activity(const Activity & act) : id(act.id) { };
+    Activity(uint64_t id) : id(id) { };
+};
+
+typedef enum {
+    evBuildCreated = 0,
+    evBuildStarted = 1,
+    evBuildOutput = 2,
+    evBuildFinished = 3,
+    evDownloadCreated = 4,
+    evDownloadDestroyed = 5,
+    evDownloadProgress = 6,
+    evDownloadSucceeded = 7,
+    evSubstitutionCreated = 8,
+    evSubstitutionStarted = 9,
+    evSubstitutionFinished = 10,
+} EventType;
+
+struct Event
+{
+    struct Field
+    {
+        // FIXME: use std::variant.
+        enum { tInt, tString } type;
+        uint64_t i = 0;
+        std::string s;
+        Field(const std::string & s) : type(tString), s(s) { }
+        Field(const char * s) : type(tString), s(s) { }
+        Field(const uint64_t & i) : type(tInt), i(i) { }
+        Field(const Activity & act) : type(tInt), i(act.id) { }
+    };
+
+    typedef std::vector<Field> Fields;
+
+    EventType type;
+    Fields fields;
+
+    std::string getS(size_t n) const
+    {
+        assert(n < fields.size());
+        assert(fields[n].type == Field::tString);
+        return fields[n].s;
+    }
+
+    uint64_t getI(size_t n) const
+    {
+        assert(n < fields.size());
+        assert(fields[n].type == Field::tInt);
+        return fields[n].i;
+    }
+};
 
 class Logger
 {
@@ -32,34 +89,16 @@ public:
 
     virtual void warn(const std::string & msg);
 
-    virtual void setExpected(const std::string & label, uint64_t value = 1) { }
-    virtual void setProgress(const std::string & label, uint64_t value = 1) { }
-    virtual void incExpected(const std::string & label, uint64_t value = 1) { }
-    virtual void incProgress(const std::string & label, uint64_t value = 1) { }
-
-private:
-
-    virtual void startActivity(Activity & activity, Verbosity lvl, const FormatOrString & fs) = 0;
-
-    virtual void stopActivity(Activity & activity) = 0;
-
-};
-
-class Activity
-{
-public:
-    Logger & logger;
-
-    Activity(Logger & logger, Verbosity lvl, const FormatOrString & fs)
-        : logger(logger)
+    template<typename... Args>
+    void event(EventType type, const Args & ... args)
     {
-        logger.startActivity(*this, lvl, fs);
+        Event ev;
+        ev.type = type;
+        nop{(ev.fields.emplace_back(Event::Field(args)), 1)...};
+        event(ev);
     }
 
-    ~Activity()
-    {
-        logger.stopActivity(*this);
-    }
+    virtual void event(const Event & ev) = 0;
 };
 
 extern Logger * logger;
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 1d1f68fc8452..16f4b232e6c5 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -372,7 +372,7 @@ void deletePath(const Path & path)
 
 void deletePath(const Path & path, unsigned long long & bytesFreed)
 {
-    Activity act(*logger, lvlDebug, format("recursively deleting path ‘%1%’") % path);
+    //Activity act(*logger, lvlDebug, format("recursively deleting path ‘%1%’") % path);
     bytesFreed = 0;
     _deletePath(path, bytesFreed);
 }
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 5a9c9513fd5c..7ea32e8d9f14 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -364,6 +364,8 @@ void ignoreException();
 #define ANSI_NORMAL "\e[0m"
 #define ANSI_BOLD "\e[1m"
 #define ANSI_RED "\e[31;1m"
+#define ANSI_GREEN "\e[32;1m"
+#define ANSI_BLUE "\e[34;1m"
 
 
 /* Filter out ANSI escape codes from the given string. If ‘nixOnly’ is