scripts: Add clean-hashserver-database script

Auxiliary script to clean the hashserver database based on the files
available in the sstate directory.

It makes used of the new "hashclient gc-mark-stream" command to mark all sstate
relevant hashes as "alive" and removes everything else from the
database.

Usage example:
```
./scripts/clean-hashserver-database \
    --sstate-dir ~/build/sstate-cache \
    --hashclient ./bitbake/bin/bitabke-hashclient \
    --hashserver-address "ws://localhost:8688/ws" \
    --mark "alive" \
    --threshold-age 60 \
    --clean-db
```

(From OE-Core rev: f6737c762ac11f7653a64fac58428428c4222d0f)

Signed-off-by: Alexander Marques <c137.marques@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/clean-hashserver-database

@@ -0,0 +1,77 @@
+#!/bin/bash
+set -euo pipefail
+
+SSTATE_DIR=""
+BB_HASHCLIENT=""
+BB_HASHSERVER=""
+
+ALIVE_DB_MARK="alive"
+CLEAN_DB="false"
+THRESHOLD_AGE="3600"
+
+function help() {
+    cat <<HELP_TEXT
+Usage: $0 --sstate-dir path --hashclient path --hashserver-address address \
+[--mark value] [--clean-db] [--threshold-age seconds]
+
+Auxiliary script remove unused or no longer relevant entries from the hashequivalence database, based
+on the files available on the sstate directory.
+
+    -h | --help)               Show this help message and exit
+    -a | --hashserver-adress)  bitbake-hashserver address
+    -c | --hashclient)         Path to bitbake-hashclient
+    -m | --mark)               Marker string to mark database entries
+    -s | --sstate-dir)         Path to the sstate dir
+    -t | --threshold-age)      Remove unused entries older than SECONDS old (default: 3600)
+    --clean-db)                Remove all unmarked and unused entries from the database
+HELP_TEXT
+}
+
+function argument_parser() {
+    while [ $# -gt 0 ]; do
+        case "$1" in
+            -h | --help) help; exit 0 ;;
+            -a | --hashserver-address) BB_HASHSERVER="$2"; shift ;;
+            -c | --hashclient) BB_HASHCLIENT="$2"; shift ;;
+            -m | --mark) ALIVE_DB_MARK="$2"; shift ;;
+            -s | --sstate-dir) SSTATE_DIR="$2"; shift ;;
+            -t | --threshold-age) THRESHOLD_AGE="$2"; shift ;;
+            --clean-db) CLEAN_DB="true";;
+            *)
+                echo "Argument '$1' is not supported" >&2
+                help >&2
+                exit 1
+                ;;
+        esac
+        shift
+    done
+
+    function validate_mandatory_argument() {
+        local var_value="$1"
+        local error_message="$2"
+
+        if [ -z "$var_value" ]; then
+            echo "$error_message"
+            help >&2
+            exit 1
+        fi
+    }
+
+    validate_mandatory_argument "$SSTATE_DIR" "Please provide the path to the sstate dir."
+    validate_mandatory_argument "$BB_HASHCLIENT" "Please provide the path to bitbake-hashclient."
+    validate_mandatory_argument "$BB_HASHSERVER" "Please provide the address of bitbake-hashserver."
+}
+
+# -- main code --
+argument_parser $@
+
+# Mark all db sstate hashes
+find "$SSTATE_DIR" -name "*.tar.zst" | \
+sed 's/.*:\([^_]*\)_.*/unihash \1/' | \
+$BB_HASHCLIENT --address "$BB_HASHSERVER" gc-mark-stream "$ALIVE_DB_MARK"
+
+# Remove unmarked and unused entries
+if [ "$CLEAN_DB" = "true" ]; then
+    $BB_HASHCLIENT --address "$BB_HASHSERVER" gc-sweep "$ALIVE_DB_MARK"
+    $BB_HASHCLIENT --address "$BB_HASHSERVER" clean-unused "$THRESHOLD_AGE"
+fi