add an example for background tasks

Author: cgsdev0

examples/bg-task/.gitignore

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+data/
+pubsub/
+uploads/

examples/bg-task/Dockerfile

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+FROM ubuntu
+
+ENV DEV false
+
+RUN apt-get update && apt-get install ucspi-tcp
+
+EXPOSE 3000
+
+COPY . /app
+
+CMD [ "/app/start.sh" ]

examples/bg-task/config.sh

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+PROJECT_NAME="Background Task"

examples/bg-task/core.sh

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+../../core.sh

examples/bg-task/pages/bg.sh

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+
+# helper function to map each
+# line of input to an SSE event
+event_stream() {
+  local line
+  while IFS= read -r line; do
+    event "$1" "$line"
+  done
+}
+
+# start a long running task in the background,
+# and pipe its output to the SSE topic 'stuff'
+#
+# important things to note:
+# 1. we close stdin at the start with '</dev/null'
+# 2. we close stdout and stderr at the end of the pipe
+
+</dev/null ./task.sh \
+  | event_stream update \
+  | publish stuff &>/dev/null &
+
+# this happens immediately; we don't need to wait
+# for the above task to finish to get this response.
+echo 'Job started!'

examples/bg-task/pages/index.sh

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+
+source config.sh
+
+htmx_page << EOF
+  <h1>${PROJECT_NAME}</h1>
+  <button hx-post="/bg" hx-target="#target">Do Stuff</button>
+  <div id="target">Not Started</div>
+  <h2>Events</h2>
+  <output hx-ext="sse" sse-connect="/sse" sse-swap="update" hx-swap="beforeend">
+EOF

examples/bg-task/pages/sse.sh

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+# sse
+
+topic() {
+  echo stuff
+}

examples/bg-task/start.sh

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+../../start.sh

examples/bg-task/static/style.css

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+body {
+  padding: 0 40px;
+}
+#signature {
+  position: absolute;
+  z-index: 100;
+  right: 20px;
+  top: 20px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+#signature a {
+  text-decoration: none;
+}
+
+#signature a:hover {
+  text-decoration: underline;
+}
+
+#signature svg {
+  width: 36px;
+  height: 36px;
+  margin-top: -4px;
+  vertical-align: middle;
+}
+
+#form {
+  display: flex;
+  max-width: 400px;
+  flex-direction: column;
+}
+
+#count {
+  font-size: 24px;
+}

examples/bg-task/task.sh

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+#!/bin/bash
+
+# simulate a binary doing background stuff
+sleep 1
+echo "hello"
+sleep 1
+echo "world"
+sleep 1
+echo "things"
+sleep 1
+echo "happened"
+sleep 1
+echo "goodbye"