src,cli: support compact (one-line) JSON reports

Multi-line JSON is more human readable, but harder for log aggregators
to consume, they usually require a log message per line, particularly
for JSON. Compact output will be consumable by aggregators such as EFK
(Elastic Search-Fluentd-Kibana), LogDNA, DataDog, etc.

PR-URL: https://github.com/nodejs/node/pull/32254
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

1 files changed, 34 insertions, 12 deletions

diff --git a/src/node_report.h b/src/node_report.h
index 46b69b9681d..808e302223e 100644
--- a/src/node_report.h
+++ b/src/node_report.h
@@ -65,17 +65,29 @@ extern double prog_start_time;
 // JSON compiler definitions.
 class JSONWriter {
  public:
-  explicit JSONWriter(std::ostream& out) : out_(out) {}
+  JSONWriter(std::ostream& out, bool compact)
+    : out_(out), compact_(compact) {}
 
+ private:
   inline void indent() { indent_ += 2; }
   inline void deindent() { indent_ -= 2; }
   inline void advance() {
+    if (compact_) return;
     for (int i = 0; i < indent_; i++) out_ << ' ';
   }
+  inline void write_one_space() {
+    if (compact_) return;
+    out_ << ' ';
+  }
+  inline void write_new_line() {
+    if (compact_) return;
+    out_ << '\n';
+  }
 
+ public:
   inline void json_start() {
     if (state_ == kAfterValue) out_ << ',';
-    out_ << '\n';
+    write_new_line();
     advance();
     out_ << '{';
     indent();
@@ -83,7 +95,7 @@ class JSONWriter {
   }
 
   inline void json_end() {
-    out_ << '\n';
+    write_new_line();
     deindent();
     advance();
     out_ << '}';
@@ -92,10 +104,12 @@ class JSONWriter {
   template <typename T>
   inline void json_objectstart(T key) {
     if (state_ == kAfterValue) out_ << ',';
-    out_ << '\n';
+    write_new_line();
     advance();
     write_string(key);
-    out_ << ": {";
+    out_ << ':';
+    write_one_space();
+    out_ << '{';
     indent();
     state_ = kObjectStart;
   }
@@ -103,23 +117,29 @@ class JSONWriter {
   template <typename T>
   inline void json_arraystart(T key) {
     if (state_ == kAfterValue) out_ << ',';
-    out_ << '\n';
+    write_new_line();
     advance();
     write_string(key);
-    out_ << ": [";
+    out_ << ':';
+    write_one_space();
+    out_ << '[';
     indent();
     state_ = kObjectStart;
   }
   inline void json_objectend() {
-    out_ << '\n';
+    write_new_line();
     deindent();
     advance();
     out_ << '}';
+    if (indent_ == 0) {
+      // Top-level object is complete, so end the line.
+      out_ << '\n';
+    }
     state_ = kAfterValue;
   }
 
   inline void json_arrayend() {
-    out_ << '\n';
+    write_new_line();
     deindent();
     advance();
     out_ << ']';
@@ -128,10 +148,11 @@ class JSONWriter {
   template <typename T, typename U>
   inline void json_keyvalue(const T& key, const U& value) {
     if (state_ == kAfterValue) out_ << ',';
-    out_ << '\n';
+    write_new_line();
     advance();
     write_string(key);
-    out_ << ": ";
+    out_ << ':';
+    write_one_space();
     write_value(value);
     state_ = kAfterValue;
   }
@@ -139,7 +160,7 @@ class JSONWriter {
   template <typename U>
   inline void json_element(const U& value) {
     if (state_ == kAfterValue) out_ << ',';
-    out_ << '\n';
+    write_new_line();
     advance();
     write_value(value);
     state_ = kAfterValue;
@@ -177,6 +198,7 @@ class JSONWriter {
 
   enum JSONState { kObjectStart, kAfterValue };
   std::ostream& out_;
+  bool compact_;
   int indent_ = 0;
   int state_ = kObjectStart;
 };