Merge pull request #19449 from JuliaLang/jb/fasterstring

faster `String` allocation

NEWS.md

@@ -33,6 +33,13 @@ Breaking changes
 
 This section lists changes that do not have deprecation warnings.
 
+  * `String`s no longer have a `.data` field (as part of a significant performance
+    improvement). Use `Vector{UInt8}(str)` to access a string as a byte array.
+    However, allocating the `Vector` object has overhead. You can also use
+    `codeunit(str, i)` to access the `i`th byte of a `String`.
+    Use `sizeof(str)` instead of `length(str.data)`, and `pointer(str)` instead of
+    `pointer(str.data)`. ([#19449])
+
   * Operations between `Float16` and `Integers` now return `Float16` instead of `Float32`. ([#17261])
 
   * Keyword arguments are processed left-to-right: if the same keyword is specified more than
@@ -818,6 +825,7 @@ Language tooling improvements
 [#19233]: https://github.com/JuliaLang/julia/issues/19233
 [#19288]: https://github.com/JuliaLang/julia/issues/19288
 [#19305]: https://github.com/JuliaLang/julia/issues/19305
+[#19449]: https://github.com/JuliaLang/julia/issues/19449
 [#19469]: https://github.com/JuliaLang/julia/issues/19469
 [#19543]: https://github.com/JuliaLang/julia/issues/19543
 [#19598]: https://github.com/JuliaLang/julia/issues/19598

base/LineEdit.jl

@@ -437,7 +437,7 @@ function splice_buffer!{T<:Integer}(buf::IOBuffer, r::UnitRange{T}, ins::Abstrac
     elseif pos > last(r)
         seek(buf, pos - length(r))
     end
-    splice!(buf.data, r + 1, ins.data) # position(), etc, are 0-indexed
+    splice!(buf.data, r + 1, Vector{UInt8}(ins)) # position(), etc, are 0-indexed
     buf.size = buf.size + sizeof(ins) - length(r)
     seek(buf, position(buf) + sizeof(ins))
 end

base/boot.jl

@@ -182,8 +182,6 @@ else
     typealias UInt UInt32
 end
 
-abstract AbstractString
-
 function Typeof end
 (f::typeof(Typeof))(x::ANY) = isa(x,Type) ? Type{x} : typeof(x)
 
@@ -192,12 +190,19 @@ type ErrorException <: Exception
     msg::AbstractString
     ErrorException(msg::AbstractString) = new(msg)
 end
+
+Expr(args::ANY...) = _expr(args...)
+
+macro _noinline_meta()
+    Expr(:meta, :noinline)
+end
+
 immutable BoundsError        <: Exception
     a::Any
     i::Any
     BoundsError() = new()
-    BoundsError(a::ANY) = new(a)
-    BoundsError(a::ANY, i::ANY) = new(a,i)
+    BoundsError(a::ANY) = (@_noinline_meta; new(a))
+    BoundsError(a::ANY, i) = (@_noinline_meta; new(a,i))
 end
 immutable DivideError        <: Exception end
 immutable DomainError        <: Exception end
@@ -221,11 +226,7 @@ end
 
 abstract DirectIndexString <: AbstractString
 
-immutable String <: AbstractString
-    data::Array{UInt8,1}
-    # required to make String("foo") work (#15120):
-    String(d::Array{UInt8,1}) = new(d)
-end
+String(s::String) = s  # no constructor yet
 
 # This should always be inlined
 getptls() = ccall(:jl_get_ptls_states, Ptr{Void}, ())
@@ -278,8 +279,6 @@ immutable VecElement{T}
 end
 VecElement{T}(arg::T) = VecElement{T}(arg)
 
-Expr(args::ANY...) = _expr(args...)
-
 # used by lowering of splicing unquote
 splicedexpr(hd::Symbol, args::Array{Any,1}) = (e=Expr(hd); e.args=args; e)
 
@@ -338,16 +337,18 @@ Array{T}(::Type{T}, m::Int)               = Array{T,1}(m)
 Array{T}(::Type{T}, m::Int,n::Int)        = Array{T,2}(m,n)
 Array{T}(::Type{T}, m::Int,n::Int,o::Int) = Array{T,3}(m,n,o)
 
-
 # primitive Symbol constructors
-Symbol(s::String) = Symbol(s.data)
+function Symbol(s::String)
+    return ccall(:jl_symbol_n, Ref{Symbol}, (Ptr{UInt8}, Int),
+                 ccall(:jl_string_ptr, Ptr{UInt8}, (Any,), s),
+                 sizeof(s))
+end
 function Symbol(a::Array{UInt8,1})
     return ccall(:jl_symbol_n, Ref{Symbol}, (Ptr{UInt8}, Int),
-          ccall(:jl_array_ptr, Ptr{UInt8}, (Any,), a),
-          Intrinsics.arraylen(a))
+                 ccall(:jl_array_ptr, Ptr{UInt8}, (Any,), a),
+                 Intrinsics.arraylen(a))
 end
 
-
 # docsystem basics
 macro doc(x...)
     atdoc(x...)
@@ -378,8 +379,8 @@ unsafe_write(io::IO, x::Ptr{UInt8}, nb::Int) =
 write(io::IO, x::UInt8) =
     (ccall(:jl_uv_putb, Void, (Ptr{Void}, UInt8), io_pointer(io), x); 1)
 function write(io::IO, x::String)
-    nb = sizeof(x.data)
-    unsafe_write(io, ccall(:jl_array_ptr, Ptr{UInt8}, (Any,), x.data), nb)
+    nb = sizeof(x)
+    unsafe_write(io, ccall(:jl_string_ptr, Ptr{UInt8}, (Any,), x), nb)
     return nb
 end
 

base/c.jl

@@ -73,21 +73,15 @@ pointer(p::Cwstring) = convert(Ptr{Cwchar_t}, p)
 ==(x::Union{Cstring,Cwstring}, y::Ptr) = pointer(x) == y
 ==(x::Ptr, y::Union{Cstring,Cwstring}) = x == pointer(y)
 
-# here, not in pointer.jl, to avoid bootstrapping problems in coreimg.jl
-unsafe_wrap(::Type{String}, p::Cstring, own::Bool=false) = unsafe_wrap(String, convert(Ptr{UInt8}, p), own)
-unsafe_wrap(::Type{String}, p::Cstring, len::Integer, own::Bool=false) =
-    unsafe_wrap(String, convert(Ptr{UInt8}, p), len, own)
 unsafe_string(s::Cstring) = unsafe_string(convert(Ptr{UInt8}, s))
 
 # convert strings to String etc. to pass as pointers
-cconvert(::Type{Cstring}, s::String) =
-    ccall(:jl_array_cconvert_cstring, Ref{Vector{UInt8}},
-          (Vector{UInt8},), s.data)
+cconvert(::Type{Cstring}, s::String) = s
 cconvert(::Type{Cstring}, s::AbstractString) =
     cconvert(Cstring, String(s)::String)
 
 function cconvert(::Type{Cwstring}, s::AbstractString)
-    v = transcode(Cwchar_t, String(s).data)
+    v = transcode(Cwchar_t, Vector{UInt8}(String(s)))
     !isempty(v) && v[end] == 0 || push!(v, 0)
     return v
 end
@@ -100,7 +94,7 @@ containsnul(p::Ptr, len) =
 containsnul(s::String) = containsnul(unsafe_convert(Ptr{Cchar}, s), sizeof(s))
 containsnul(s::AbstractString) = '\0' in s
 
-function unsafe_convert(::Type{Cstring}, s::Vector{UInt8})
+function unsafe_convert(::Type{Cstring}, s::Union{String,Vector{UInt8}})
     p = unsafe_convert(Ptr{Cchar}, s)
     containsnul(p, sizeof(s)) &&
         throw(ArgumentError("embedded NULs are not allowed in C strings: $(repr(s))"))
@@ -133,7 +127,7 @@ same argument.
 This is only available on Windows.
 """
 function cwstring(s::AbstractString)
-    bytes = String(s).data
+    bytes = Vector{UInt8}(String(s))
     0 in bytes && throw(ArgumentError("embedded NULs are not allowed in C strings: $(repr(s))"))
     return push!(transcode(UInt16, bytes), 0)
 end
@@ -170,7 +164,7 @@ function transcode{S<:Union{Int32,UInt32}}(::Type{UInt8}, src::Vector{S})
     take!(buf)
 end
 transcode(::Type{String}, src::String) = src
-transcode(T, src::String) = transcode(T, src.data)
+transcode(T, src::String) = transcode(T, Vector{UInt8}(src))
 transcode(::Type{String}, src) = String(transcode(UInt8, src))
 
 function transcode(::Type{UInt16}, src::Vector{UInt8})
@@ -257,7 +251,7 @@ function transcode(::Type{UInt8}, src::Vector{UInt16})
         a = src[i += 1]
     end
 
-    dst = Array{UInt8}(m)
+    dst = StringVector(m)
     a = src[1]
     i, j = 1, 0
     while true

base/datafmt.jl

@@ -129,7 +129,7 @@ function readdlm_auto(input::AbstractString, dlm::Char, T::Type, eol::Char, auto
         # TODO: It would be nicer to use String(a) without making a copy,
         # but because the mmap'ed array is not NUL-terminated this causes
         # jl_try_substrtod to segfault below.
-        return readdlm_string(String(copy(a)), dlm, T, eol, auto, optsd)
+        return readdlm_string(unsafe_string(pointer(a),length(a)), dlm, T, eol, auto, optsd)
     else
         return readdlm_string(readstring(input), dlm, T, eol, auto, optsd)
     end
@@ -153,7 +153,7 @@ type DLMOffsets <: DLMHandler
         offsets = Array{Array{Int,1}}(1)
         offsets[1] = Array{Int}(offs_chunk_size)
         thresh = ceil(min(typemax(UInt), Base.Sys.total_memory()) / sizeof(Int) / 5)
-        new(offsets, 1, thresh, length(sbuff.data))
+        new(offsets, 1, thresh, sizeof(sbuff))
     end
 end
 
@@ -220,7 +220,7 @@ end
 
 _chrinstr(sbuff::String, chr::UInt8, startpos::Int, endpos::Int) =
     (endpos >= startpos) && (C_NULL != ccall(:memchr, Ptr{UInt8},
-    (Ptr{UInt8}, Int32, Csize_t), pointer(sbuff.data)+startpos-1, chr, endpos-startpos+1))
+    (Ptr{UInt8}, Int32, Csize_t), pointer(sbuff)+startpos-1, chr, endpos-startpos+1))
 
 function store_cell{T}(dlmstore::DLMStore{T}, row::Int, col::Int,
         quoted::Bool, startpos::Int, endpos::Int)
@@ -463,17 +463,9 @@ function colval{T<:Char}(sbuff::String, startpos::Int, endpos::Int, cells::Array
 end
 colval(sbuff::String, startpos::Int, endpos::Int, cells::Array, row::Int, col::Int) = true
 
-function dlm_parse{T,D}(dbuff::T, eol::D, dlm::D, qchar::D, cchar::D,
-                        ign_adj_dlm::Bool, allow_quote::Bool, allow_comments::Bool,
-                        skipstart::Int, skipblanks::Bool, dh::DLMHandler)
-    all_ascii = (D <: UInt8) || (isascii(eol) &&
-                                 isascii(dlm) &&
-                                 (!allow_quote || isascii(qchar)) &&
-                                 (!allow_comments || isascii(cchar)))
-    if T === String && all_ascii
-        return dlm_parse(dbuff.data, eol % UInt8, dlm % UInt8, qchar % UInt8, cchar % UInt8,
-                         ign_adj_dlm, allow_quote, allow_comments, skipstart, skipblanks, dh)
-    end
+function dlm_parse{D}(dbuff::String, eol::D, dlm::D, qchar::D, cchar::D,
+                      ign_adj_dlm::Bool, allow_quote::Bool, allow_comments::Bool,
+                      skipstart::Int, skipblanks::Bool, dh::DLMHandler)
     ncols = nrows = col = 0
     is_default_dlm = (dlm == invalid_dlm(D))
     error_str = ""

base/deepcopy.jl

@@ -22,6 +22,15 @@ function deepcopy_internal(x::SimpleVector, stackdict::ObjectIdDict)
     return y
 end
 
+function deepcopy_internal(x::String, stackdict::ObjectIdDict)
+    if haskey(stackdict, x)
+        return stackdict[x]
+    end
+    y = unsafe_string(pointer(x), sizeof(x))
+    stackdict[x] = y
+    return y
+end
+
 function deepcopy_internal(x::ANY, stackdict::ObjectIdDict)
     T = typeof(x)::DataType
     nf = nfields(T)

base/deprecated.jl

@@ -430,7 +430,7 @@ end
                 endn += 1
             end
             (endn > idx) && (endn -= 1)
-            splice!(a, idx:endn, invalids_as.data)
+            splice!(a, idx:endn, Vector{UInt8}(invalids_as))
             l = length(a)
         end
         String(a)
@@ -1499,4 +1499,17 @@ end
 # Calling promote_op is likely a bad idea, so deprecate its convenience wrapper promote_eltype_op
 @deprecate promote_eltype_op(op, As...) promote_op(op, map(eltype, As)...)
 
+function unsafe_wrap(::Type{String}, p::Union{Ptr{UInt8},Ptr{Int8}}, len::Integer, own::Bool=false)
+    Base.depwarn("unsafe_wrap(String, ...) is deprecated; use `unsafe_string` instead.", :unsafe_wrap)
+    #ccall(:jl_array_to_string, Ref{String}, (Any,),
+    #      ccall(:jl_ptr_to_array_1d, Vector{UInt8}, (Any, Ptr{UInt8}, Csize_t, Cint),
+    #            Vector{UInt8}, p, len, own))
+    unsafe_string(p, len)
+end
+unsafe_wrap(::Type{String}, p::Union{Ptr{UInt8},Ptr{Int8}}, own::Bool=false) =
+    unsafe_wrap(String, p, ccall(:strlen, Csize_t, (Ptr{UInt8},), p), own)
+unsafe_wrap(::Type{String}, p::Cstring, own::Bool=false) = unsafe_wrap(String, convert(Ptr{UInt8}, p), own)
+unsafe_wrap(::Type{String}, p::Cstring, len::Integer, own::Bool=false) =
+    unsafe_wrap(String, convert(Ptr{UInt8}, p), len, own)
+
 # End deprecations scheduled for 0.6

base/error.jl

@@ -73,7 +73,7 @@ macro assert(ex, msgs...)
     elseif !isempty(msgs) && (isa(msg, Expr) || isa(msg, Symbol))
         # message is an expression needing evaluating
         msg = :(Main.Base.string($(esc(msg))))
-    elseif isdefined(Main, :Base) && isdefined(Main.Base, :string)
+    elseif isdefined(Main, :Base) && isdefined(Main.Base, :string) && applicable(Main.Base.string, msg)
         msg = Main.Base.string(msg)
     else
         # string() might not be defined during bootstrap

base/exports.jl

@@ -778,6 +778,7 @@ export
     chomp,
     chop,
     chr2ind,
+    codeunit,
     dec,
     digits,
     digits!,

base/expr.jl

@@ -9,9 +9,8 @@ Generates a symbol which will not conflict with other variable names.
 """
 gensym() = ccall(:jl_gensym, Ref{Symbol}, ())
 
-gensym(s::String) = gensym(s.data)
-gensym(a::Array{UInt8,1}) =
-    ccall(:jl_tagged_gensym, Ref{Symbol}, (Ptr{UInt8}, Int32), a, length(a))
+gensym(s::String) = ccall(:jl_tagged_gensym, Ref{Symbol}, (Ptr{UInt8}, Int32), s, sizeof(s))
+
 gensym(ss::String...) = map(gensym, ss)
 gensym(s::Symbol) =
     ccall(:jl_tagged_gensym, Ref{Symbol}, (Ptr{UInt8}, Int32), s, ccall(:strlen, Csize_t, (Ptr{UInt8},), s))

base/fft/FFTW.jl

@@ -282,7 +282,10 @@ sprint_plan_{T<:fftwDouble}(plan::FFTWPlan{T}) =
 sprint_plan_{T<:fftwSingle}(plan::FFTWPlan{T}) =
     ccall((:fftwf_sprint_plan,libfftwf), Ptr{UInt8}, (PlanPtr,), plan)
 function sprint_plan(plan::FFTWPlan)
-    unsafe_wrap(String, sprint_plan_(plan), true)
+    p = sprint_plan_(plan)
+    str = unsafe_string(p)
+    Libc.free(p)
+    return str
 end
 
 function show{T,K,inplace}(io::IO, p::cFFTWPlan{T,K,inplace})

base/filesystem.jl

@@ -173,9 +173,9 @@ function readbytes!(f::File, b::Array{UInt8}, nb=length(b))
     uv_error("read",ret)
     return ret
 end
-read(io::File) = read!(io, Array{UInt8}(nb_available(io)))
+read(io::File) = read!(io, Base.StringVector(nb_available(io)))
 readavailable(io::File) = read(io)
-read(io::File, nb::Integer) = read!(io, Array{UInt8}(min(nb, nb_available(io))))
+read(io::File, nb::Integer) = read!(io, Base.StringVector(min(nb, nb_available(io))))
 
 const SEEK_SET = Int32(0)
 const SEEK_CUR = Int32(1)

base/gmp.jl

@@ -532,8 +532,10 @@ hex(n::BigInt, pad::Int) = base(16, n, pad)
 
 function base(b::Integer, n::BigInt)
     2 <= b <= 62 || throw(ArgumentError("base must be 2 ≤ base ≤ 62, got $b"))
-    p = ccall((:__gmpz_get_str,:libgmp), Ptr{UInt8}, (Ptr{UInt8}, Cint, Ptr{BigInt}), C_NULL, b, &n)
-    unsafe_wrap(String, p, true)
+    nd = ndigits(n, b)
+    str = Base._string_n(n < 0 ? nd+1 : nd)
+    ccall((:__gmpz_get_str,:libgmp), Ptr{UInt8}, (Ptr{UInt8}, Cint, Ptr{BigInt}), str, b, &n)
+    return str
 end
 
 function base(b::Integer, n::BigInt, pad::Integer)

base/interactiveutil.jl

@@ -773,6 +773,8 @@ function summarysize(obj::Array, seen, excl)
     return size
 end
 
+summarysize(s::String, seen, excl) = sizeof(Int) + sizeof(s)
+
 function summarysize(obj::SimpleVector, seen, excl)
     key = pointer_from_objref(obj)
     haskey(seen, key) ? (return 0) : (seen[key] = true)

base/intfuncs.jl

@@ -377,7 +377,7 @@ string(x::Union{Int8,Int16,Int32,Int64,Int128}) = dec(x)
 
 function bin(x::Unsigned, pad::Int, neg::Bool)
     i = neg + max(pad,sizeof(x)<<3-leading_zeros(x))
-    a = Array{UInt8}(i)
+    a = StringVector(i)
     while i > neg
         a[i] = '0'+(x&0x1)
         x >>= 1
@@ -389,7 +389,7 @@ end
 
 function oct(x::Unsigned, pad::Int, neg::Bool)
     i = neg + max(pad,div((sizeof(x)<<3)-leading_zeros(x)+2,3))
-    a = Array{UInt8}(i)
+    a = StringVector(i)
     while i > neg
         a[i] = '0'+(x&0x7)
         x >>= 3
@@ -401,7 +401,7 @@ end
 
 function dec(x::Unsigned, pad::Int, neg::Bool)
     i = neg + max(pad,ndigits0z(x))
-    a = Array{UInt8}(i)
+    a = StringVector(i)
     while i > neg
         a[i] = '0'+rem(x,10)
         x = oftype(x,div(x,10))
@@ -413,7 +413,7 @@ end
 
 function hex(x::Unsigned, pad::Int, neg::Bool)
     i = neg + max(pad,(sizeof(x)<<1)-(leading_zeros(x)>>2))
-    a = Array{UInt8}(i)
+    a = StringVector(i)
     while i > neg
         d = x & 0xf
         a[i] = '0'+d+39*(d>9)
@@ -433,7 +433,7 @@ function base(b::Int, x::Unsigned, pad::Int, neg::Bool)
     2 <= b <= 62 || throw(ArgumentError("base must be 2 ≤ base ≤ 62, got $b"))
     digits = b <= 36 ? base36digits : base62digits
     i = neg + max(pad,ndigits0z(x,b))
-    a = Array{UInt8}(i)
+    a = StringVector(i)
     while i > neg
         a[i] = digits[1+rem(x,b)]
         x = div(x,b)