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Let img tiles be downloaded async. #2010

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Merged
joa-quim merged 1 commit into from
Jun 24, 2026
+30 −5
Merged

Let img tiles be downloaded async. #2010

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35 changes: 30 additions & 5 deletions src/imgtiles.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -504,9 +504,13 @@ function mosaic(lon::Vector{<:Float64}, lat::Vector{<:Float64}; pt_radius=637813
img = getImgTile(quadkey, quad_[1], tile_url, cache, cache_supp, ext, isZXY, verbose)
else
img = zeros(UInt8, (256 * nMo, 256 * mMo, 3))
for row = 1:mMo # Rows
for col = 1:nMo # Cols
img[(col-1)*256+1:col*256, (row-1)*256+1:row*256, :] =
tiledir = string(cache, cache_supp) # Pre-create cache dir once to avoid a concurrent mkpath race
(!isempty(cache) && !isdir(tiledir)) && mkpath(tiledir)
# Cooperative @async (NOT @threads): GDAL is not thread-safe, but Downloads.download yields to the
# scheduler during the network wait, so the tile fetches overlap while the C code stays serialized.
@sync for row = 1:mMo # Rows
for col = 1:nMo # Cols
@async img[(col-1)*256+1:col*256, (row-1)*256+1:row*256, :] =
getImgTile(quadkey, quad_[row, col], tile_url[row, col], cache, cache_supp, ext, isZXY, verbose)
end
end
Expand Down Expand Up @@ -979,6 +983,27 @@ function getLonLat(pixelX, pixelY, zoomL)
return lon, lat
end

# -----------------------------------------------------------------------------------------
"""
Optional sink for per-tile fetch messages. When set to a `Function`, `mosaic`'s
`"Downloading file ..."` / `"Retrieving file from cache: ..."` notes are routed to it (emitted at
full verbosity, regardless of `verbose`) instead of being printed to stdout. Lets a host GUI show
tile activity without an fd-level stdout redirect (which corrupts the C tile fetch). `nothing`
(default) -> normal `verbose`-gated `println`.
"""
const TILE_LOGGER = Ref{Union{Nothing,Function}}(nothing)

# Emit a tile-fetch progress note: to TILE_LOGGER if set (always), else println when verbose>=level.
function _tilemsg(verbose::Int, level::Int, msg::AbstractString)
lg = TILE_LOGGER[]
if lg !== nothing
try; lg(msg); catch; end
elseif verbose >= level
println(msg)
end
return
end

# -----------------------------------------------------------------------------------------
function getImgTile(quadkey, quadtree, url, cache, cache_supp, ext, isZXY, verbose)::Array{UInt8,3}
# Get the image either from a local cache or by url
Expand All @@ -992,7 +1017,7 @@ function getImgTile(quadkey, quadtree, url, cache, cache_supp, ext, isZXY, verbo
fname = string(cache, cache_supp, filesep, quadtree, ".", ext)

if isfile(fname)
(verbose > 1) && println("Retrieving file from cache: ", fname)
_tilemsg(verbose, 2, string("Retrieving file from cache: ", fname))
_img = gdalread(fname)
else
_img = netFetchTile(url, string(cache, cache_supp), quadtree, ext, verbose)
Expand Down Expand Up @@ -1020,7 +1045,7 @@ end
# -----------------------------------------------------------------------------------------
function netFetchTile(url, cache, quadtree, ext, verbose)
# Fetch a file from the web either using gdal or Downloads (when gdal is not able to)
(verbose > 0) && println("Downloading file ", url)
_tilemsg(verbose, 1, string("Downloading file ", url))
try
dest_fiche = "lixogrr" # Don't recall anymore what this default, defaults for!
if !isempty(cache)
Expand Down
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