Add i-PI server calculator and update i-PI driver to AB v0.4 (#31)

* driver update

* initial server draft

* AtomsCalculators interface and some fixes

* ipi server working

* fixes

* tests

* update tests

* fix unixsocket

* add doc string for server

* fix

src/ipi/ipi_interface.jl

@@ -9,9 +9,18 @@ using Unitful
 using UnitfulAtomic
 
 export run_driver
+export IPIcalculator
 
 const hdrlen = 12
-const pos_type = typeof(SVector(1., 1., 1.)u"bohr") #should be bohr
+
+# Define context untits for better conversions
+const bohr = Unitful.ContextUnits(u"bohr", u"Å")
+const hartree = Unitful.ContextUnits(u"hartree", u"eV")
+
+
+const pos_type      = typeof( zero( SVector{3, Float64} ) * bohr ) 
+const force_el_type = typeof( zero( SVector{3, Float64} ) * (hartree/bohr) )
+const virial_type   = typeof( zero( SMatrix{3, 3, Float64} ) * hartree )
 
 function sendmsg(comm, message; nbytes=hdrlen)
     @info "Sending message" message
@@ -51,42 +60,94 @@ function recvinit(comm)
     )
 end
 
+function send_init(comm)
+    @info "Sending INIT"
+    write(comm, one(Int32))
+    str = "ok"
+    write(comm, sizeof(str))
+    write(comm, str)
+    return true
+end
+
 
 function recvposdata(comm)
-    raw_cell = read(comm, 9*8)
-    raw_icell = read(comm, 9*8) # drop this (inverce cell)
+    raw_cell = read(comm, 9*sizeof(Float64))
+    raw_icell = read(comm, 9*sizeof(Float64)) # drop this (inverce cell)
     natoms = read(comm, Int32)
-    raw_pos = read(comm, 8*3*natoms)
+    raw_pos = read(comm, sizeof(Float64)*3*natoms)
     data_cell = reinterpret(pos_type, raw_cell)
     data_pos = reinterpret(pos_type, raw_pos)
     @info "Position data recieved"
     return (;
-        :cell => Vector(data_cell),
+        :cell => Tuple(Vector(data_cell)),
         :positions => Vector(data_pos)  # clean type a little bit
     )
 end
 
+function send_pos_data(comm, sys)
+    @info "Sending position data"
+    box_tmp = vcat(bounding_box(sys)...)
+    box = (Float64 ∘ ustrip).(u"bohr", box_tmp)
+    write(comm, box)
+    write(comm, zeros(3,3) )  #inverse cell that is to be dropped
+    l = length(sys)
+    write(comm, Int32(l) )
+    pos = map( 1:l ) do i 
+        SVector{3, Float64}(ustrip.(u"bohr", position(sys, i)))
+    end
+    write(comm, pos)
+    @info "Position data sent"
+    return true
+end
+
 
 function sendforce(comm, e::Number, forces::AbstractVector, virial::AbstractMatrix)
     etype = (eltype ∘ eltype)(forces)
     f_tmp = reinterpret(reshape, etype, forces)
     sendmsg(comm, "FORCEREADY")
-    write(comm, ustrip(u"hartree", e) )
+    write(comm, (Float64 ∘ ustrip)(u"hartree", e) )
     write(comm, Int32( length(forces) ) )
-    write(comm, ustrip.(u"hartree/bohr", f_tmp) )
-    write(comm, ustrip.(u"hartree", virial) )
+    write(comm, (Float64 ∘ ustrip).(u"hartree/bohr", f_tmp) )
+    write(comm, (Float64 ∘ ustrip).(u"hartree", virial) )
 
     # Send single byte at end to make sure we are alive
     write(comm, one(Int32) )
     write(comm, zero(UInt8) )
 end
 
+
+function recv_force(comm)
+    sendmsg(comm, "GETFORCE")
+    mess = recvmsg(comm)
+    if mess == "FORCEREADY"
+        @info "Recieving forces"
+        e = read(comm, Float64)
+        n = read(comm, Int32)
+        f_raw = read(comm, sizeof(Float64)*3*n)
+        v_raw = read(comm, sizeof(Float64)*9)
+
+        # Reading end message that is dropped
+        i = read(comm, Int32)
+        _ = read(comm, i)
+
+        f = reinterpret(force_el_type, f_raw) |> Vector
+        v = reinterpret(virial_type, v_raw)[1]
+        return (
+            energy = e * hartree,
+            forces = f,
+            virial = v
+        )
+    else
+        error("Expected \"FORCEREADY\", but received \"$mess\"")
+    end
+end
+
 """
-    run_driver(address, calculator, init_structure; port=31415, unixsocket=false )
+    run_driver(address, calculator, init_structure; port=31415, unixsocket=false, basename="/tmp/ipi_" )
 
 Connect I-PI driver to server at given `address`. Use kword `port` (default 31415) to
-specify port. If kword `unixsocket` is true, `address` is understood to be the name of the socket
-and `port` option is ignored.
+specify port. If kword `unixsocket` is true, `basename*address` is understood to be the name of the socket
+and `port` option is ignored. 
 
 You need to give initial structure as I-PI protocol does not transfer atom symbols.
 This means that, if you want to change the number of atoms or their symbols, you need
@@ -95,22 +156,21 @@ to lauch a new driver.
 Calculator events are logged at info level by default. If you do not want them to be logged,
 change logging status for IPI module.
 """
-function run_driver(address, calc, init_structure; port=31415, unixsocket=false )
+function run_driver(address, calc, init_structure; port=31415, unixsocket=false, basename="/tmp/ipi_" )
     if unixsocket
-        comm = connect("/tmp/ipi_"*address)
+        comm = connect(basename*address)
     else
         comm = connect(address, port)
     end
     has_init = true  # we have init structure as an input
     has_data = false
     data = nothing
 
-    masses = atomic_mass(init_structure)
-    symbols = atomic_symbol(init_structure)
-    anumbers = atomic_number(init_structure)
-    positions = position(init_structure)
-    cell = bounding_box(init_structure)
-    pbc =  boundary_conditions(init_structure)
+    pbc = periodicity(init_structure)
+    masses = mass(init_structure, :)
+    atom_species = species(init_structure, :)
+    positions = position(init_structure, :)
+    box = bounding_box(init_structure)
 
 
     while true
@@ -132,9 +192,9 @@ function run_driver(address, calc, init_structure; port=31415, unixsocket=false
         elseif header == "POSDATA"
             pos = recvposdata(comm)
             positions = pos[:positions]
-            cell = pos[:cell]
-            @assert length(symbols) == length(positions) "received amount of position data does no match the atomic symbol data"
-            system = FastSystem(cell, pbc, positions, symbols, anumbers, masses)
+            box = pos[:cell]
+            @assert length(atom_species) == length(positions) "received amount of position data does no match the atomic symbol data"
+            system = FastSystem(box, pbc, positions, atom_species, masses)
             data = AtomsCalculators.energy_forces_virial(system, calc)
             has_data = true
         elseif header == "GETFORCE"
@@ -151,3 +211,109 @@ function run_driver(address, calc, init_structure; port=31415, unixsocket=false
 
     end
 end
+
+
+
+## Server specific part
+
+"""
+    IPIcalculator(address=ip"127.0.0.1"; port=31415, unixsocket=false, basename="/tmp/ipi_" )
+
+Creates i-PI https://ipi-code.org/ server that works as an AtomsCalculators compatible calculators
+once i-PI driver has been connected.
+
+By default the calculator will log protocol calls to the client. If you want to suppress these,
+you need to change the logging level of IPI module.
+
+# Args
+- `address=ip"127.0.0.1"`   -  server address, if `unixsocket=true` is considered as unixsocket address
+
+# Kwargs
+- `basename="/tmp/ipi_"`    -  prefixed to address if `unixsocket=true`
+- `port=31415`              -  network port the server is using
+- `unixsocket=false`        -  use unixsocket for the connection
+"""
+mutable struct IPIcalculator{TS, TC}
+    server::TS
+    sock::TC
+    function IPIcalculator(address=ip"127.0.0.1"; port=31415, unixsocket=false, basename="/tmp/ipi_" )
+        server, sock = start_ipi_server(address; port=port, unixsocket=unixsocket, basename=basename)
+        new{typeof(server), typeof(sock)}(server, sock)
+    end
+end
+
+function start_ipi_server(address; port=31415, unixsocket=false, basename="/tmp/ipi_", tries=5 )
+    @info "Starting i-PI server"
+    server = nothing
+    if unixsocket
+        server = listen(basename*address)
+    else
+        server = listen(address, port)
+    end
+    get_connection(server; tries=tries) # returns server, socket
+end
+
+function get_connection(server; tries=5)
+    sock = accept(server)
+    i = 1
+    while isopen(sock) || i < tries
+        sendmsg(sock, "STATUS")
+        mess = recvmsg(sock)
+        if mess == "NEEDINIT"
+            sendmsg(sock, "INIT")
+            send_init(sock)
+            continue
+        elseif mess == "READY"
+            return server, sock
+        else
+            i += 1
+            close(sock)
+            sock = accept(server)
+        end
+    end
+    error("Could not form a connection to a working i-PI driver")
+end
+
+
+function AtomsCalculators.energy_forces_virial(sys, ipi::IPIcalculator; kwargs...)
+    if ! isopen(ipi.sock)
+        @info "reconnecting to i-PI driver"
+        _, sock = get_connection(ipi.server)
+        ipi.sock = sock
+    end
+    sendmsg(ipi.sock, "POSDATA")
+    send_pos_data(ipi.sock, sys)
+    sendmsg(ipi.sock, "STATUS")
+    mess = recvmsg(ipi.sock)
+    if mess == "HAVEDATA"
+        return recv_force(ipi.sock)
+    else
+        error("Expected \"HAVEDATA\", but received \"$mess\"")
+    end
+end
+
+
+AtomsCalculators.@generate_interface function AtomsCalculators.potential_energy(sys, ipi::IPIcalculator; kwargs...)
+    tmp = AtomsCalculators.energy_forces_virial(sys, ipi)
+    return tmp.energy
+end
+
+AtomsCalculators.@generate_interface function AtomsCalculators.forces(sys, ipi::IPIcalculator; kwargs...)
+    tmp = AtomsCalculators.energy_forces_virial(sys, ipi)
+    return tmp.forces
+end
+
+AtomsCalculators.@generate_interface function AtomsCalculators.virial(sys, ipi::IPIcalculator; kwargs...)
+    tmp = AtomsCalculators.energy_forces_virial(sys, ipi)
+    return tmp.virial
+end
+
+function AtomsCalculators.energy_forces(sys, ipi::IPIcalculator; kwargs...)
+    tmp = AtomsCalculators.energy_forces_virial(sys, ipi)
+    return tmp
+end
+
+
+
+AtomsCalculators.energy_unit(::IPIcalculator) = hartree
+AtomsCalculators.length_unit(::IPIcalculator) = bohr

test/runtests.jl

@@ -9,5 +9,6 @@ using Unitful
 @testset "AtomsCalculatorsUtilities.jl" begin
     @testset "Calculators" begin include("test_calculators.jl") end
     @testset "PairPotentials" begin include("test_pairpotential.jl") end
+    @testset "i-PI driver and server" begin include("test_ipi.jl")  end
     # @testset "FD Tests" begin include("test_fdtests.jl") end
 end

test/test_ipi.jl

@@ -0,0 +1,52 @@
+using AtomsBase
+using AtomsCalculators
+using AtomsCalculators.Testing
+using AtomsCalculatorsUtilities.IPI
+using AtomsCalculatorsUtilities.PairPotentials
+using Unitful
+using Base.Threads
+
+
+hydrogen = isolated_system([
+    :H => [0.1, 0, 0.]u"Å",
+    :H => [0, 0, 1.]u"Å",
+    :H => [4., 0, 0.]u"Å",
+    :H => [4., 1., 0.]u"Å"
+])
+
+box = (
+    [10.0, 0., 0.]u"Å",
+    [0.0, 10., 0.]u"Å",
+    [0.0, 0., 10.]u"Å",
+)
+
+pbc = (false, false, false)
+
+hydrogen = FlexibleSystem(hydrogen[:], bounding_box=box, periodicity=pbc)
+
+
+V = SimplePairPotential(
+    x-> (x-0.9)^2-1,
+    1,
+    1,
+    2.0u"Å"
+)
+
+
+ipi_future = @spawn IPIcalculator(port=33415)
+sleep(1) # we need to yeald to start the server
+
+ipi_driver = @spawn run_driver("127.0.0.1", V, hydrogen; port=33415)
+sleep(1) # we need to yeald to connect to the server
+
+calc = fetch(ipi_future)
+
+##
+
+test_energy_forces_virial(hydrogen, calc)
+
+@test AtomsCalculators.potential_energy(hydrogen, V) ≈ AtomsCalculators.potential_energy(hydrogen, calc)
+f_v   = AtomsCalculators.forces(hydrogen, V)
+f_ipi = AtomsCalculators.forces(hydrogen, calc)
+@test all( isapprox.(f_v, f_ipi) )
+@test AtomsCalculators.virial(hydrogen, V) ≈ AtomsCalculators.virial(hydrogen, calc)