Initial version

4 files changed, 218 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..f911417
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,86 @@
+.POSIX:
+DATE         = 1970-01-01
+VERSION      = 0.1.0
+NAME         = q
+NAME_UC      = $(NAME)
+LANGUAGES    = en
+## Installation prefix.  Defaults to "/usr".
+PREFIX       = /usr
+BINDIR       = $(PREFIX)/bin
+LIBDIR       = $(PREFIX)/lib
+INCLUDEDIR   = $(PREFIX)/include
+SRCDIR       = $(PREFIX)/src/$(NAME)
+SHAREDIR     = $(PREFIX)/share
+LOCALEDIR    = $(SHAREDIR)/locale
+MANDIR       = $(SHAREDIR)/man
+EXEC         = ./
+## Where to store the installation.  Empty by default.
+DESTDIR      =
+LDLIBS       =
+
+
+
+.SUFFIXES:
+
+
+
+all:
+include deps.mk
+
+sources = \
+	$(sources.sh)                  \
+
+
+derived-assets = \
+
+side-assets = \
+
+
+
+## Default target.  Builds all artifacts required for testing
+## and installation.
+all: $(derived-assets)
+
+
+
+check-unit:
+
+
+check-integration:
+
+
+## Run all tests.  Each test suite is isolated, so that a parallel
+## build can run tests at the same time.  The required artifacts
+## are created if missing.
+check: check-unit check-integration
+
+
+
+## Remove *all* derived artifacts produced during the build.
+## A dedicated test asserts that this is always true.
+clean:
+	rm -rf $(derived-assets) $(side-assets)
+
+
+## Installs into $(DESTDIR)$(PREFIX).  Its dependency target
+## ensures that all installable artifacts are crafted beforehand.
+install: all
+	mkdir -p \
+		'$(DESTDIR)$(BINDIR)'     \
+		'$(DESTDIR)$(SRCDIR)'
+	cp $(sources.sh)     '$(DESTDIR)$(BINDIR)'
+	cp $(sources.sh)     '$(DESTDIR)$(SRCDIR)'
+
+
+## Uninstalls from $(DESTDIR)$(PREFIX).  This is a perfect mirror
+## of the "install" target, and removes *all* that was installed.
+## A dedicated test asserts that this is always true.
+uninstall:
+	rm -rf \
+		'$(DESTDIR)$(SRCDIR)'
+	for f in $(sources.sh); do \
+		rm -f '$(DESTDIR)$(BINDIR)'/"$${f#src/}"; \
+	done
+
+
+ALWAYS:
diff --git a/deps.mk b/deps.mk
new file mode 100644
index 0000000..028851e
--- /dev/null
+++ b/deps.mk
@@ -0,0 +1,3 @@
+sources.sh = \
+	src/q \
+
diff --git a/mkdeps.sh b/mkdeps.sh
new file mode 100755
index 0000000..8204798
--- /dev/null
+++ b/mkdeps.sh
@@ -0,0 +1,13 @@
+#!/bin/sh
+set -eu
+
+export LANG=POSIX.UTF-8
+
+varlist() {
+	printf '%s = \\\n' "$1"
+	sort | sed 's|^\(.*\)$|\t\1 \\|'
+	printf '\n'
+}
+
+
+find src/* -type f -perm -111 | varlist 'sources.sh'
diff --git a/src/q b/src/q
new file mode 100755
index 0000000..17fb37d
--- /dev/null
+++ b/src/q
@@ -0,0 +1,116 @@
+#!/bin/sh
+set -eu
+
+
+usage() {
+	echo 'Usage: q TOPIC ACTION [OPTION]'
+}
+
+CONSUMER='default-consumer'
+while getopts 'C:' flag; do
+	case "$flag" in
+		C)
+			CONSUMER="$OPTARG"
+			;;
+		*)
+			usage >&2
+			exit 2
+			;;
+	esac
+done
+shift $((OPTIND - 1))
+
+TOPIC="${1:-}"
+ACTION="${2:-}"
+
+eval "$(assert-arg -- "$TOPIC"  'TOPIC')"
+eval "$(assert-arg -- "$ACTION" 'ACTION')"
+
+
+Q_DIR="${Q_DIR:-$XDG_DATA_HOME/q}/topics/$TOPIC"
+mkdir -p "$Q_DIR"
+cd "$Q_DIR"
+
+mkdir -p tmp cur dead/"$CONSUMER" offset/"$CONSUMER"
+
+for f in n offset/"$CONSUMER"/n; do
+	if [ ! -e "$f" ]; then
+		echo 0 > "$f"
+	fi
+done
+
+
+case "$ACTION" in
+	in)
+		N="$(cat n)"
+		ID="$(uuid)"
+		cat > tmp/"$ID"
+		mv tmp/"$ID" cur/"$N"
+		echo $((N + 1)) > n
+		;;
+	out)
+		N="$(cat offset/"$CONSUMER"/n)"
+		if [ ! -e cur/"$N" ]; then
+			exit 3
+		fi
+		cat cur/"$N"
+		;;
+	commit)
+		N="$(cat offset/"$CONSUMER"/n)"
+		if [ ! -e cur/"$N" ]; then
+			exit 3
+		fi
+		echo $((N + 1)) > offset/"$CONSUMER"/n
+		;;
+	dead)
+		N="$(cat offset/"$CONSUMER"/n)"
+		if [ ! -e cur/"$N" ]; then
+			exit 3
+		fi
+		touch "dead/$CONSUMER/$N"
+		echo $((N + 1)) > offset/"$CONSUMER"/n
+		;;
+	ls-dead)
+		(
+			cd dead/"$CONSUMER"/
+			find * 2>/dev/null | sort -n
+		)
+		;;
+	cat)
+		eval "$(assert-arg -- "${3:-}" 'N')"
+		OLD_N="$3"
+		if [ ! -e cur/"$OLD_N" ]; then
+			exit 3
+		fi
+		cat cur/"$OLD_N"
+		;;
+	revive)
+		eval "$(assert-arg -- "${3:-}" 'N')"
+		OLD_N="$3"
+		if [ ! -e dead/"$CONSUMER"/"$OLD_N" ]; then
+			exit 3
+		fi
+		N="$(cat n)"
+		ln -s "$OLD_N" cur/"$N"
+		echo $((N + 1)) > n
+		rm -f dead/"$CONSUMER"/"$OLD_N"
+		;;
+	size)
+		cat n
+		;;
+	offset)
+		cat offset/"$CONSUMER"/n
+		;;
+	has-data)
+		! cmp -s n offset/"$CONSUMER"/n
+		;;
+	reset)
+		eval "$(assert-arg -- "${3:-}" 'N')"
+		N="$3"
+		echo "$N" > offset/"$CONSUMER"/n
+		;;
+	*)
+		echo "Bad ACTION: $ACTION" >&2
+		exit 2
+		;;
+esac