#
__init() {
- if ! include "mutex"; then
+ if ! include "is" "mutex" "wmutex" "log"; then
return 1
fi
declare -xgr __sem_path="$TOOLBOX_HOME/sem"
+ if ! mkdir -p "$__sem_path"; then
+ return 1
+ fi
+
return 0
}
-
-_sem_mutexpath() {
- local sem
-
- sem="$1"
+_sem_get_path() {
+ local sem="$1"
if [[ "$sem" == *"/"* ]]; then
- echo "$sem.mutex"
+ echo "$sem"
else
- echo "$__sem_path/$sem.mutex"
+ echo "$__sem_path/$sem"
fi
}
-_sem_ownerpath() {
- local sem
+_sem_get_waitlock() {
+ local sem="$1"
- sem="$1"
+ echo "$(_sem_get_path "$sem")/waitlock"
+}
- if [[ "$sem" == *"/"* ]]; then
- echo "$sem.owner"
- else
- echo "$__sem_path/$sem.owner"
- fi
+_sem_get_countlock() {
+ local sem="$1"
+
+ echo "$(_sem_get_path "$sem")/countlock"
}
-_sem_sempath() {
- local sem
+_sem_get_owner() {
+ local sem="$1"
- sem="$1"
+ echo "$(_sem_get_path "$sem")/owner"
+}
- if [[ "$sem" == *"/"* ]]; then
- echo "$sem"
- else
- echo "$__sem_path/$sem"
- fi
+_sem_get_counter() {
+ local sem="$1"
+
+ echo "$(_sem_get_path "$sem")/counter"
}
-_sem_inc() {
- local sem
- local value
+_sem_counter_inc() {
+ local sem="$1"
- sem="$1"
+ local value
- if ! value=$(cat "$sem"); then
+ if ! value=$(< "$sem"); then
return 1
fi
- ((value++))
+ ((++value))
if ! echo "$value" > "$sem"; then
return 1
return 0
}
-_sem_dec() {
- local sem
- local value
+_sem_counter_dec() {
+ local sem="$1"
- sem="$1"
+ local value
- if ! value=$(cat "$sem"); then
+ if ! value=$(< "$sem"); then
return 1
fi
- if (( value == 0 )); then
+ if (( --value < 0 )); then
return 1
fi
- ((value--))
-
if ! echo "$value" > "$sem"; then
return 1
fi
}
sem_init() {
- local name
- local value
+ local name="$1"
+ local value="$2"
- local mutex
local sem
+ local waitlock
+ local countlock
+ local counter
local owner
local err
- name="$1"
- value="$2"
- err=0
+ err=1
- mutex=$(_sem_mutexpath "$name")
- sem=$(_sem_sempath "$name")
- owner=$(_sem_ownerpath "$name")
+ sem=$(_sem_get_path "$name")
+ waitlock=$(_sem_get_waitlock "$name")
+ countlock=$(_sem_get_countlock "$name")
+ counter=$(_sem_get_counter "$name")
+ owner=$(_sem_get_owner "$name")
- if ! [[ "$value" =~ ^[0-9]+$ ]]; then
+ if ! is_digits "$value"; then
+ log_debug "Initial value must be numeric"
return 1
fi
- if ! mkdir -p "${sem%/*}"; then
+ if ! mkdir "$sem"; then
+ log_error "Semaphore $sem exists"
return 1
fi
- # If the semaphore is new, locking must succeed,
- # otherwise it was not a new semaphore
- if ! mutex_trylock "$mutex"; then
- log_error "Could not acquire $mutex"
- return 1
+ if ! mutex_trylock "$countlock"; then
+ log_error "Could not acquire $countlock"
+ else
+ # If value is greater than zero, the next call to sem_wait() does
+ # not have to wait for a sem_post() to happen. Hence the waitlock
+ # does not need to be locked.
+
+ if ! mutex_trylock "$owner"; then
+ log_error "Could not acquire mutex $owner"
+ elif (( value == 0 )) && ! wmutex_trylock "$waitlock"; then
+ log_error "Could not acquire wmutex $waitlock"
+ elif ! echo "$value" > "$counter"; then
+ log_error "Could not write counter $counter"
+ else
+ err=0
+ fi
+
+ mutex_unlock "$countlock"
fi
- if ! mutex_trylock "$owner"; then
- log_error "Could not acquire $mutex"
- err=1
- elif ! echo "$value" > "$sem"; then
- err=1
+ if (( err != 0 )); then
+ if ! rm -rf "$sem"; then
+ log_error "Could not remove $sem"
+ fi
fi
- mutex_unlock "$mutex"
return "$err"
}
sem_destroy() {
- local name
+ local name="$1"
- local mutex
local sem
local owner
- name="$1"
+ sem=$(_sem_get_path "$name")
+ owner=$(_sem_get_owner "$name")
- mutex=$(_sem_mutexpath "$name")
- sem=$(_sem_sempath "$name")
- owner=$(_sem_ownerpath "$name")
-
- # Make sure only the owner can destroy the semaphore
if ! mutex_unlock "$owner"; then
+ log_debug "Could not unlock $owner"
return 1
fi
- if ! rm -f "$mutex" "$sem"; then
+ if ! rm -rf "$sem"; then
+ log_error "Could not remove $sem"
return 1
fi
}
sem_wait() {
- local name
+ local name="$1"
- local mutex
- local sem
- local passed
+ local waitlock
+ local countlock
+ local counter
+ local err
- name="$1"
+ waitlock=$(_sem_get_waitlock "$name")
+ countlock=$(_sem_get_countlock "$name")
+ counter=$(_sem_get_counter "$name")
+ err=1
- mutex=$(_sem_mutexpath "$name")
- sem=$(_sem_sempath "$name")
- passed=false
+ if ! wmutex_lock "$waitlock"; then
+ return 1
+ fi
- while ! "$passed"; do
- mutex_lock "$mutex"
+ if mutex_lock "$countlock"; then
+ local count
- if _sem_dec "$sem"; then
- passed=true
- fi
+ _sem_counter_dec "$counter"
- mutex_unlock "$mutex"
+ # if count was greater than 1, we need to unlock the waitlock
+ # because there won't be anyone calling sem_post()
- # Workaround to prevent busy-waiting. The semaphore
- # might get increased before we get to the inotifywait,
- # in which case we'd wait for a whole second, during
- # which another process might pass the semaphore. This
- # is not ideal, but to prevent this we'd need something
- # like pthread_cond_wait().
- if ! "$passed"; then
- inotifywait -qq -t 1 "$sem"
+ count=$(<"$counter")
+ if (( count > 0 )); then
+ wmutex_unlock "$waitlock"
fi
- done
- return 0
+ mutex_unlock "$countlock"
+ err=0
+ fi
+
+ return "$err"
}
sem_trywait() {
- local name
-
- local mutex
- local sem
- local res
-
- name="$1"
+ local name="$1"
- mutex=$(_sem_mutexpath "$name")
- sem=$(_sem_sempath "$name")
- res=1
+ local waitlock
+ local countlock
+ local counter
+ local err
- mutex_lock "$mutex"
+ waitlock=$(_sem_get_waitlock "$name")
+ countlock=$(_sem_get_countlock "$name")
+ counter=$(_sem_get_counter "$name")
+ err=1
- if _sem_dec "$sem"; then
- res=0
+ if ! wmutex_trylock "$waitlock"; then
+ return 1
fi
- mutex_unlock "$mutex"
+ if mutex_lock "$countlock"; then
+ _sem_counter_dec "$counter"
+ mutex_unlock "$countlock"
+ err=0
+ fi
- return "$res"
+ return "$err"
}
sem_post() {
- local name
+ local name="$1"
- local mutex
- local sem
+ local waitlock
+ local countlock
+ local counter
local err
- local value
- name="$1"
+ waitlock=$(_sem_get_waitlock "$name")
+ countlock=$(_sem_get_countlock "$name")
+ counter=$(_sem_get_counter "$name")
+ err=1
- mutex=$(_sem_mutexpath "$name")
- sem=$(_sem_sempath "$name")
- err=0
+ if mutex_lock "$countlock"; then
+ _sem_counter_inc "$counter"
+ mutex_unlock "$countlock"
- mutex_lock "$mutex"
+ if [ -L "$waitlock" ]; then
+ wmutex_unlock "$waitlock"
+ fi
- if ! _sem_inc "$sem"; then
- err=1
+ err=0
fi
- mutex_unlock "$mutex"
-
return "$err"
}
sem_peek() {
local name="$1"
- local mutex
- local sem
+ local countlock
+ local counter
local value
local err
- mutex=$(_sem_mutexpath "$name")
- sem=$(_sem_sempath "$name")
- err=false
+ countlock=$(_sem_get_countlock "$name")
+ counter=$(_sem_get_counter "$name")
+ err=1
- mutex_lock "$mutex"
+ if mutex_lock "$countlock"; then
+ if value=$(<"$counter"); then
+ err=0
+ fi
- if ! value=$(<"$sem"); then
- err=true
+ mutex_unlock "$countlock"
fi
- mutex_unlock "$mutex"
-
- if "$err"; then
- return 1
+ if (( err == 0 )); then
+ echo "$value"
fi
- echo "$value"
- return 0
+ return "$err"
}
--- /dev/null
+#!/usr/bin/env bats
+
+. toolbox.sh
+include "sem"
+
+setup() {
+ delete=()
+ return 0
+}
+
+teardown() {
+ if (( ${#delete[@]} > 0 )); then
+ rm -rf "${delete[@]}"
+ fi
+
+ return 0
+}
+
+@test "sem00: _sem_get_path() returns the path of a private semaphore if name does not contain slashes" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge"
+ expectation="$__sem_path/$name"
+ reality=$(_sem_get_path "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem01: _sem_get_path() returns the path of a public semaphore if name contains a slash" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge/hoge"
+ expectation="$name"
+ reality=$(_sem_get_path "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem02: _sem_get_waitlock() returns the path of a private semaphore's waitlock" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge"
+ expectation="$__sem_path/$name/waitlock"
+ reality=$(_sem_get_waitlock "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem03: _sem_get_waitlock() returns the path of a public semaphore's waitlock" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge/hoge"
+ expectation="$name/waitlock"
+ reality=$(_sem_get_waitlock "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem04: _sem_get_countlock() returns the path of a private semaphore's countlock" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge"
+ expectation="$__sem_path/$name/countlock"
+ reality=$(_sem_get_countlock "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem05: _sem_get_countlock() returns the path of a public semaphore's countlock" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge/hoge"
+ expectation="$name/countlock"
+ reality=$(_sem_get_countlock "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem06: _sem_get_owner() returns the path of a private semaphore's owner mutex" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge"
+ expectation="$__sem_path/$name/owner"
+ reality=$(_sem_get_owner "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem07: _sem_get_owner() returns the path of a public semaphore's owner mutex" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge/hoge"
+ expectation="$name/owner"
+ reality=$(_sem_get_owner "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem08: _sem_get_counter() returns path of a private semaphore's counter" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge"
+ expectation="$__sem_path/$name/counter"
+ reality=$(_sem_get_counter "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem09: _sem_get_counter() returns path of a public semaphore's counter" {
+ local name
+ local expectation
+ local reality
+
+ name="hoge/hoge"
+ expectation="$name/counter"
+ reality=$(_sem_get_counter "$name")
+
+ [[ "$expectation" == "$reality" ]]
+}
+
+@test "sem10: _sem_counter_inc() increases the counter" {
+ local counter
+ local value
+ local i
+
+ counter=$(mktemp)
+ delete+=("$counter")
+
+ value=0
+ echo "$value" > "$counter"
+
+ for (( i = 1; i <= 64; i++ )); do
+ _sem_counter_inc "$counter"
+ value=$(<"$counter")
+ (( value == i ))
+ done
+}
+
+@test "sem11: _sem_counter_dec() decreases the counter" {
+ local counter
+ local value
+ local i
+
+ counter=$(mktemp)
+ delete+=("$counter")
+
+ value=64
+ echo "$value" > "$counter"
+
+ for (( i = 63; i >= 0; i-- )); do
+ _sem_counter_dec "$counter"
+ value=$(<"$counter")
+ (( value == i ))
+ done
+}
+
+@test "sem12: sem_init() creates a private semaphore" {
+ local path
+ local name
+
+ name="test_sem12_$RANDOM"
+ path=$(_sem_get_path "$name")
+
+ ! [ -d "$path" ]
+ sem_init "$name" 0
+ [ -d "$path" ]
+
+ delete+=("$path")
+}
+
+@test "sem13: sem_init() creates a public semaphore" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+ name="$path/test_sem13"
+
+ ! [ -d "$name" ]
+ sem_init "$name" 0
+ [ -d "$name" ]
+}
+
+@test "sem14: sem_init() creates a private semaphore" {
+ local path
+ local name
+
+ name="test_sem14_$RANDOM"
+ path=$(_sem_get_path "$name")
+
+ ! [ -d "$name" ]
+ sem_init "$name" 0
+ [ -d "$path" ]
+
+ delete+=("$path")
+}
+
+@test "sem15: sem_init() locks the waitlock if value is 0" {
+ local path
+ local name
+ local waitlock
+
+ path=$(mktemp -d)
+ delete+=("$path")
+ name="$path/test_sem15"
+
+ sem_init "$name" 0
+
+ waitlock=$(_sem_get_waitlock "$name")
+
+ [ -L "$waitlock" ]
+}
+
+@test "sem16: sem_init() does not lock the waitlock if value > 0" {
+ local path
+ local i
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ for (( i = 1; i <= 8; i++ )); do
+ local name
+ local waitlock
+
+ name="$path/test_sem16_$i"
+ waitlock=$(_sem_get_waitlock "$name")
+
+ sem_init "$name" "$i"
+
+ ! [ -L "$waitlock" ]
+ done
+}
+
+@test "sem17: sem_init() does not lock the countlock" {
+ local path
+ local i
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ for (( i = 0; i < 8; i++ )); do
+ local name
+ local countlock
+
+ name="$path/test_sem17_$i"
+ countlock=$(_sem_get_countlock "$name")
+
+ sem_init "$name" "$i"
+
+ ! [ -L "$countlock" ]
+ done
+}
+
+@test "sem18: sem_init() sets the semaphore's counter" {
+ local path
+ local i
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ for (( i = 0; i < 8; i++ )); do
+ local name
+ local counter
+ local value
+
+ name="$path/test_sem18_$i"
+ counter=$(_sem_get_counter "$name")
+
+ sem_init "$name" "$i"
+
+ value=$(<"$counter")
+ (( value == i ))
+ done
+}
+
+@test "sem19: sem_init() sets the ownerlock" {
+ local path
+ local name
+ local ownerlock
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem19"
+ ownerlock=$(_sem_get_owner "$name")
+
+ sem_init "$name" 0
+
+ [ -L "$ownerlock" ]
+}
+
+@test "sem20: sem_init() makes the current process owner of the semaphore" {
+ local path
+ local name
+ local ownerlock
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem20"
+ ownerlock=$(_sem_get_owner "$name")
+
+ sem_init "$name" 0
+
+ owner=$(readlink "$ownerlock")
+ (( BASHPID == owner ))
+}
+
+@test "sem21: sem_init() makes the subshell owner of the semaphore" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem21"
+
+ (
+ local ownerlock
+ local owner
+
+ sem_init "$name" 0
+ ownerlock=$(_sem_get_owner "$name")
+ owner=$(readlink "$ownerlock")
+
+ (( owner == BASHPID ))
+ (( owner != $$ ))
+ )
+}
+
+@test "sem22: sem_init() fails if value is missing" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem22"
+
+ ! sem_init "$name"
+}
+
+@test "sem23: sem_init() fails if value is not numeric" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem23"
+
+ ! sem_init "$name" "test"
+}
+
+@test "sem24: sem_init() fails if value is negative" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem24"
+
+ ! sem_init "$name" -1
+}
+
+@test "sem25: sem_init() does not create a semaphore if the value is missing" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem25"
+
+ ! sem_init "$name"
+ ! [ -e "$name" ]
+}
+
+@test "sem26: sem_init() does not create a semaphore if the value is not numeric" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem26"
+
+ ! sem_init "$name" "test"
+ ! [ -e "$name" ]
+}
+
+@test "sem27: sem_init() does not create a semaphore if the value is negative" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem27"
+
+ ! sem_init "$name" -1
+ ! [ -e "$name" ]
+}
+
+@test "sem28: sem_destroy() destroys semaphore if called by owner" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem28"
+
+ sem_init "$name" 0
+
+ [ -e "$name" ]
+ sem_destroy "$name"
+ ! [ -e "$name" ]
+}
+
+@test "sem29: sem_destroy() does not destroy another process's semaphore" {
+ local path
+ local name
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem29"
+
+ sem_init "$name" 0
+ [ -e "$name" ]
+ ! ( sem_destroy "$name" )
+ [ -e "$name" ]
+}
+
+@test "sem30: sem_post() increases the counter by one" {
+ local name
+ local path
+ local counter
+ local i
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem30"
+ counter=$(_sem_get_counter "$name")
+
+ sem_init "$name" 0
+
+ for (( i = 1; i <= 16; i++ )); do
+ local value
+
+ sem_post "$name"
+ value=$(<"$counter")
+
+ (( value == i ))
+ done
+}
+
+@test "sem31: sem_wait() decreases the counter by one" {
+ local name
+ local path
+ local counter
+ local i
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem31"
+ counter=$(_sem_get_counter "$name")
+
+ sem_init "$name" 16
+
+ for (( i = 15; i >= 0; i-- )); do
+ local value
+
+ sem_wait "$name"
+ value=$(<"$counter")
+
+ (( value == i ))
+ done
+}
+
+@test "sem32: sem_wait() locks the waitlock if the counter is 1" {
+ local name
+ local path
+ local waitlock
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem32"
+ waitlock=$(_sem_get_waitlock "$name")
+
+ sem_init "$name" 1
+ sem_wait "$name"
+ [ -L "$waitlock" ]
+}
+
+@test "sem33: sem_wait() releases the waitlock if the counter is greater than 1" {
+ local name
+ local path
+ local waitlock
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem33"
+ waitlock=$(_sem_get_waitlock "$name")
+
+ sem_init "$name" 2
+ sem_wait "$name"
+ ! [ -L "$waitlock" ]
+}
+
+@test "sem34: sem_peek() returns the counter of a semaphore" {
+ local name
+ local path
+ local i
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ name="$path/test_sem34"
+
+ sem_init "$name" 0
+
+ for (( i = 1; i <= 16; i++ )); do
+ local counter
+
+ sem_post "$name"
+ counter=$(sem_peek "$name")
+ (( counter == i ))
+ done
+}
+
+@test "sem35: sem_post() wakes up sem_wait()" {
+ local sem
+ local path
+ local ppid
+ local cpid
+ local timeout
+
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ sem="$path/test_sem35"
+
+ sem_init "$sem" 0
+
+ ( sem_wait "$sem" ) &
+ cpid="$!"
+ ( sem_post "$sem" ) &
+
+ for (( timeout = 10; timeout > 0; timeout-- )); do
+ if ! ps -p "$cpid" &> /dev/null; then
+ return 0
+ fi
+
+ sleep 1
+ done
+
+ kill -9 "$cpid"
+ return 1
+}
+
+@test "sem36: sem_wait() is woken up by sem_post()" {
+ local sem
+ local path
+ local ppid
+ local cpid
+ local timeout
+
+ path=$(mktemp -d)
+ delete+=("$path")
+
+ timeout=10
+ sem="$path/test_sem36"
+
+ sem_init "$sem" 0
+
+ ( sem_post "$sem" ) &
+ ( sem_wait "$sem" ) &
+ cpid="$!"
+
+ for (( timeout = 10; timeout > 0; timeout-- )); do
+ if ! ps -p "$cpid" &> /dev/null; then
+ return 0
+ fi
+
+ sleep 1
+ done
+
+ kill -9 "$cpid"
+ return 1
+}
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