DS⁺: Reliable Distributed Snapshot Algorithm for Wireless Sensor Networks

Algorithm 2

Reliable transmission of snapshot messages.

While  𝑡_𝑠 not expired do

 if receive(𝑆_𝑖,𝑆_{⌊(𝑖−1)/2⌋},𝑀_red) = true then

  While  𝑖≠0  do

   Wait for 𝑡_𝑐,𝑖

   sendU(𝑆_𝑖,𝑆_{⌊(𝑖−1)/2⌋},𝑀_white,𝑖)

   𝑖←⌊(𝑖−1)/2⌋

  end while

 else if receive(𝑆_𝑖,𝑆_{⌊(𝑖−1)/2⌋},𝑀_rt) = true then

  if  𝑀_white,𝑖⋅payload = null then

   Take snapshot sn

   𝑀_white,𝑖⋅payload = sn

  end if

  While  𝑖≠0  do

   sendU(𝑆_𝑖,𝑆_{⌊(𝑖−1)/2⌋},𝑀_white,𝑖)

   𝑖←⌊(𝑖−1)/2⌋

  end while

 end if

end while