Make spillway OTP 27 compatible

Author: raz-adroll

.github/workflows/erlang.yml

@@ -7,9 +7,8 @@ env:
 
 jobs:
 
-  build:
-
-    runs-on: ubuntu-20.04
+  OTP25:
+    runs-on: ubuntu-24.04
 
     strategy:
       matrix:
@@ -24,12 +23,44 @@ jobs:
         otp-version: ${{matrix.otp}}
         rebar3-version: ${{matrix.rebar}}
     - name: Restore _build
-      uses: actions/cache@v2
+      uses: actions/cache@v4
+      with:
+        path: _build
+        key: _build-cache-for-os-${{runner.os}}-otp-${{steps.setup-beam.outputs.otp-version}}-rebar3-${{steps.setup-beam.outputs.rebar3-version}}-hash-${{hashFiles('rebar.lock')}}
+    - name: Restore rebar3's cache
+      uses: actions/cache@v4
+      with:
+        path: ~/.cache/rebar3
+        key: rebar3-cache-for-os-${{runner.os}}-otp-${{steps.setup-beam.outputs.otp-version}}-rebar3-${{steps.setup-beam.outputs.rebar3-version}}-hash-${{hashFiles('rebar.lock')}}
+    - name: Compile
+      run: rebar3 compile
+    - name: Format check
+      run: rebar3 format --verify
+    - name: Run tests and verifications
+      run: rebar3 test
+
+  OTP27:
+    runs-on: ubuntu-24.04
+
+    strategy:
+      matrix:
+        otp: ['27.3.4']
+        rebar: ['3.24.0']
+
+    steps:
+    - uses: actions/checkout@v2
+    - uses: erlef/setup-beam@v1
+      id: setup-beam
+      with:
+        otp-version: ${{matrix.otp}}
+        rebar3-version: ${{matrix.rebar}}
+    - name: Restore _build
+      uses: actions/cache@v4
       with:
         path: _build
         key: _build-cache-for-os-${{runner.os}}-otp-${{steps.setup-beam.outputs.otp-version}}-rebar3-${{steps.setup-beam.outputs.rebar3-version}}-hash-${{hashFiles('rebar.lock')}}
     - name: Restore rebar3's cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ~/.cache/rebar3
         key: rebar3-cache-for-os-${{runner.os}}-otp-${{steps.setup-beam.outputs.otp-version}}-rebar3-${{steps.setup-beam.outputs.rebar3-version}}-hash-${{hashFiles('rebar.lock')}}

src/spillway_srv.erl

@@ -70,7 +70,21 @@ enter(Name, Size, Limit) when Size > 0 ->
 %% The counter must already exist.
 -spec leave(term(), non_neg_integer()) -> non_neg_integer().
 leave(Name, Size) ->
-    ets:update_counter(?TID, Name, {#counter.value, -Size, 0, 0}).
+    Counter =
+        case ets:update_counter(?TID, Name, {#counter.value, -Size, 0, 0}) of
+            [] ->
+                0;
+            [Result | _] ->
+                Result;
+            Result ->
+                Result
+        end,
+    case Counter >= 0 of
+        true ->
+            Counter;
+        false ->
+            0
+    end.
 
 %% Return the current counter value.
 -spec cur(term()) -> non_neg_integer().