perf_hooks: implement histogram based api

Add a sampling-based event loop delay monitor.

```js
const { monitorEventLoopDelay } = require('perf_hooks');

const h = monitorEventLoopDelay();

h.enable();

h.disable();

console.log(h.percentiles);
console.log(h.min);
console.log(h.max);
console.log(h.mean);
console.log(h.stddev);
console.log(h.percentile(50));
```

PR-URL: https://github.com/nodejs/node/pull/25378
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 45 insertions, 0 deletions

diff --git a/LICENSE b/LICENSE
index f75f7581d3..53176c8164 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1371,3 +1371,48 @@ The externally maintained libraries used by Node.js are:
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     THE SOFTWARE.
   """
+
+- HdrHistogram, located at deps/histogram, is licensed as follows:
+  """
+    The code in this repository code was Written by Gil Tene, Michael Barker,
+    and Matt Warren, and released to the public domain, as explained at
+    http://creativecommons.org/publicdomain/zero/1.0/
+
+    For users of this code who wish to consume it under the "BSD" license
+    rather than under the public domain or CC0 contribution text mentioned
+    above, the code found under this directory is *also* provided under the
+    following license (commonly referred to as the BSD 2-Clause License). This
+    license does not detract from the above stated release of the code into
+    the public domain, and simply represents an additional license granted by
+    the Author.
+
+    -----------------------------------------------------------------------------
+    ** Beginning of "BSD 2-Clause License" text. **
+
+     Copyright (c) 2012, 2013, 2014 Gil Tene
+     Copyright (c) 2014 Michael Barker
+     Copyright (c) 2014 Matt Warren
+     All rights reserved.
+
+     Redistribution and use in source and binary forms, with or without
+     modification, are permitted provided that the following conditions are met:
+
+     1. Redistributions of source code must retain the above copyright notice,
+        this list of conditions and the following disclaimer.
+
+     2. Redistributions in binary form must reproduce the above copyright notice,
+        this list of conditions and the following disclaimer in the documentation
+        and/or other materials provided with the distribution.
+
+     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+     AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+     IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+     ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+     LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+     CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+     SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+     INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+     THE POSSIBILITY OF SUCH DAMAGE.
+  """