[rfc] Resource-limited Nodes (#1677)

* Limited-resource RFC.

* Add to introduction

* Add question about constrained template use

* More work on introduction

* Primarily whitespace cleanup.

* Standardize thread-(un)safe

* Add blurb on C++20 support

* Updates to serialization RFC

* Incomplete version of sequence diagram

* Expand on limited resources

* Update README.md

* Update image

* Update README.md

* Minor updates

* Add performance analysis to README

* Whitespace cleanup

* Adjust heading levels

* Minor edits to text

* Adjust levels one more time

* Final editing pass before PR

* Remove unused plantuml files

* Adjust PR based on Mike's and Konstantin's suggestions/questions

* Adjust GitHub markdown

* Adjust GitHub markdown...again

* Update proposal based on @akukanov's suggestion

* Include graph diagram of analyzed workflow

* Use png instead

* Show graph with limiters

---------

Co-authored-by: Kyle Knoepfel <[email protected]>

Author: marcpaterno

rfcs/proposed/flow_graph_serializers/README.md

@@ -0,0 +1,110 @@
+digraph {
+  rankdir=LR
+  ranksep=2
+
+  node [fontname="Arial"]
+  Source [label=<<b>Source</b>> style="filled" shape="cylinder" fillcolor="#666666" fontcolor="white"]
+
+  node [shape="box" peripheries=2]
+  DB [label=<<b>DB</b><br/> 2 tokens>]
+  ROOT [label=<<b>ROOT</b><br/> 1 token>]
+  GENIE [label=<<b>GENIE</b><br/> 1 token>]
+
+  {rank=same; Source; DB; ROOT; GENIE}
+
+  node [shape="box" style=filled width=2.7 peripheries=1]
+
+  propagating [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Propagating</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="lightblue">unlimited</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT"><i>(none)</i></td></tr>
+      </table>
+    >
+    fillcolor="#BF5B17"
+    fontcolor="white"
+  ]
+
+  histogramming [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Histogramming</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="lightblue">unlimited</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT">ROOT</td></tr>
+      </table>
+    >
+    fillcolor="#F02A7F"
+    fontcolor="white"
+  ]
+
+  generating [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Generating</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="blue">unlimited</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT">GENIE</td></tr>
+      </table>
+    >
+    fillcolor="#FFFD99"
+  ]
+
+  histo_generating [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Histo-generating</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="lightblue">unlimited</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT">ROOT, GENIE</td></tr>
+      </table>
+    >
+    fillcolor="#386CB0"
+    fontcolor="white"
+  ]
+
+  calA [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Calibration[A]</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="blue">unlimited</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT">DB</td></tr>
+      </table>
+    >
+    fillcolor="#7FC97F"
+  ]
+
+  calB [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Calibration[B]</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="blue">unlimited</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT">DB</td></tr>
+      </table>
+    >
+    fillcolor="#BEAED4"
+  ]
+
+  calC [
+    label=<
+      <table cellpadding="0" border="0" cellborder="0">
+         <tr><td align="LEFT" colspan="2"><b>Calibration[C]</b></td></tr>
+         <tr><td align="LEFT">Concurrency:</td><td align="LEFT"><font color="red">serial</font></td></tr>
+         <tr><td align="LEFT">Resources:</td><td align="LEFT">DB</td></tr>
+      </table>
+    >
+    fillcolor="#FDC086"
+  ]
+
+  Source -> {
+    calA
+    calB
+    calC
+    generating
+    histo_generating
+    histogramming
+    propagating
+  }
+
+  GENIE -> {generating histo_generating} -> GENIE [style="dotted" color="blue" arrowhead="empty"]
+  ROOT -> {histogramming histo_generating} -> ROOT [style="dotted" color="blue" arrowhead="empty"]
+  DB -> {calA calB calC} -> DB [style="dotted" color="blue" arrowhead="empty"]
+}

rfcs/proposed/flow_graph_serializers/README.qmd

@@ -0,0 +1,46 @@
+/*-- scss:defaults --*/
+
+// $presentation-font-size-root: 32px;
+
+@import url('https://fonts.googleapis.com/css2?family=Crimson+Pro:ital,wght@0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&display=swap');
+
+$font-family-serif: "Crimson Pro", serif;
+$presentation-heading-font: "Crimson Pro", serif;
+$font-family-serif: "Crimson Pro", serif;
+$link-color: #1111ff;
+$red: #dc1111;
+
+/*-- scss:rules --*/
+
+.cell-output {
+  border: 1px solid #ccc;
+  padding: 0.5em;
+}
+
+.reveal .alert {
+  color: $red;
+}
+
+.reveal .slide-number {
+  // color: $link-color;
+  font-size: 0.8em !important;
+}
+
+.reveal .title-slide h1 {
+  text-align: center;
+}
+
+.reveal .footer {
+  font-size: 0.8em !important;
+  text-align: center !important;
+}
+
+.reveal code {
+  // Monospaced fonts typically are larger than
+  font-size: smaller;
+}
+
+.reveal .sourceCode {
+  // This is used for code blocks, not inline code
+  font-size: smaller;
+}

rfcs/proposed/flow_graph_serializers/README_files/figure-commonmark/fig-delay-distribution-1.png

@@ -0,0 +1,33 @@
+read_times <- function(fname) {
+  readr::read_tsv(fname, col_types = "ciccii") |>
+    dplyr::mutate(
+      time = as.numeric(lubridate::hms(time)),
+      thread = as.factor(thread),
+      event = as.factor(event),
+      node = as.factor(node)
+    ) |>
+    dplyr::mutate(time = time - min(time)) |>
+    dplyr::mutate(time = 1000 * time)
+}
+
+scale_x_log10_nice <- function(...) {
+  ggplot2::scale_x_log10(
+    breaks = scales::trans_breaks("log10", function(x) 10^x),
+    labels = scales::trans_format("log10", scales::math_format(10^.x))
+  )
+}
+
+scale_y_log10_nice <- function(...) {
+  ggplot2::scale_y_log10(
+    breaks = scales::trans_breaks("log10", function(x) 10^x),
+    labels = scales::trans_format("log10", scales::math_format(10^.x))
+  )
+}
+
+# Produce a vector of "black" or "white" for each given color, so that they
+# can be used as labels that contrast with the given color.
+get_contrast_color <- function(color) {
+  rgb <- col2rgb(color) / 255
+  luminance <- 0.2126 * rgb[1] + 0.7152 * rgb[2] + 0.0722 * rgb[3]
+  if (luminance > 0.5) "black" else "white"
+}