From 790ecf54464cf1d38cbcf26cca9836b53e6556fa Mon Sep 17 00:00:00 2001
From: Andre Henriques <andr3h3nriqu3s@gmail.com>
Date: Thu, 16 Nov 2023 11:57:42 +0000
Subject: [PATCH] Initial commit

---
 .formatter.exs              |  4 ++
 .gitignore                  | 26 ++++++++++
 eager_reliable_broadcast.ex | 95 +++++++++++++++++++++++++++++++++++++
 mix.exs                     | 28 +++++++++++
 4 files changed, 153 insertions(+)
 create mode 100644 .formatter.exs
 create mode 100644 .gitignore
 create mode 100644 eager_reliable_broadcast.ex
 create mode 100644 mix.exs

diff --git a/.formatter.exs b/.formatter.exs
new file mode 100644
index 0000000..d2cda26
--- /dev/null
+++ b/.formatter.exs
@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..67efd20
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,26 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+distributed_system_coursework-*.tar
+
+# Temporary files, for example, from tests.
+/tmp/
diff --git a/eager_reliable_broadcast.ex b/eager_reliable_broadcast.ex
new file mode 100644
index 0000000..75c69e4
--- /dev/null
+++ b/eager_reliable_broadcast.ex
@@ -0,0 +1,95 @@
+defmodule EagerReliableBroadcast do
+    def start(name, processes) do
+        pid = spawn(EagerReliableBroadcast, :init, [name, processes])
+        # :global.unregister_name(name)
+        case :global.re_register_name(name, pid) do
+            :yes -> pid  
+            :no  -> :error
+        end
+        IO.puts "registered #{name}"
+        pid
+    end
+
+    # Init event must be the first
+    # one after the component is created
+    def init(name, processes) do 
+        state = %{ 
+            name: name, 
+            processes: processes,
+            delivered: %{},  # Use this data structure to remember IDs of the delivered messages
+            seq_no: 0 # Use this variable to remember the last sequence number used to identify a message
+        }
+        run(state)
+    end
+
+    def run(state) do
+        state = receive do 
+            # Handle the broadcast request event
+            {:broadcast, m} -> 
+                IO.puts("#{inspect state.name}: RB-broadcast: #{inspect m}")
+                # Create a unique message identifier from state.name and state.seqno.
+                # Create a new data message data_msg from the given payload m
+                # the message identifier.
+                # Update the state as necessary
+                data_msg = {:data, state.name, state.seq_no, m}
+                
+                # Use the provided beb_broadcast function to propagate data_msg to 
+
+                # all process
+                beb_broadcast(data_msg, state.processes)
+                %{state | seq_no: state.seq_no + 1 }
+
+            {:data, proc, seq_no, m} ->
+              if not Map.has_key?(state.delivered, {proc, seq_no, m}) do
+                data_msg = {:data, proc, seq_no, m}
+                beb_broadcast(data_msg, state.processes)
+                unicast({:deliver, proc, m}, state.name)
+                %{state | delivered: Map.put(state.delivered, {proc, seq_no, m}, 1)}
+              else
+                val = Map.get(state.delivered, {proc, seq_no, m})
+                if val < Enum.count(state.processes) do
+                  %{state | delivered: Map.put(state.delivered, {proc, seq_no, m}, val + 1)}
+                else
+                  %{state | delivered: Map.delete(state.delivered, {proc, seq_no, m})}
+                end
+              end
+
+               # If <proc, seqno> was already delivered, do nothing.
+               # Otherwise, update delivered, generate a deliver event for the
+               # upper layer, and re-broadcast (echo) the received message.
+               # In both cases, do not forget to return the state.
+
+            {:deliver, proc, m} ->
+                # Simulate the deliver indication event
+                IO.puts("#{inspect state.name}: RB-deliver: #{inspect m} from #{inspect proc}")
+                state
+        end
+        run(state)
+    end
+
+
+    defp unicast(m, p) do
+        case :global.whereis_name(p) do
+                pid when is_pid(pid) -> send(pid, m)
+                :undefined -> :ok
+        end
+    end
+
+    defp beb_broadcast(m, dest), do: for p <- dest, do: unicast(m, p)
+
+    # You can use this function to simulate a process failure.
+    # name: the name of this process
+    # proc_to_fail: the name of the failed process
+    # fail_send_to: list of processes proc_to_fail will not be broadcasting messages to
+    # Note that this list must include proc_to_fail.
+    # m and dest are the same as the respective arguments of the normal
+    # beb_broadcast.
+    defp beb_broadcast_with_failures(name, proc_to_fail, fail_send_to, m, dest) do
+        if name == proc_to_fail do
+            for p <- dest, p not in fail_send_to, do: unicast(m, p)
+        else
+            for p <- dest, p != proc_to_fail, do: unicast(m, p)
+        end
+    end
+
+end
diff --git a/mix.exs b/mix.exs
new file mode 100644
index 0000000..e1db2db
--- /dev/null
+++ b/mix.exs
@@ -0,0 +1,28 @@
+defmodule DistributedSystemCoursework.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :distributed_system_coursework,
+      version: "0.1.0",
+      elixir: "~> 1.15",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end