Merge pull request #15 from djes/djes

Rewrite of cache mechanism
2017-06-15 16:42:15 +02:00
parent ff72bc8f07 4183dcd59b
commit 0319c8b5a4
3 changed files with 605 additions and 466 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 PBMap.pb.bak
+*.exe
--- a/PBMap.pb
+++ b/PBMap.pb
@@ -47,6 +47,7 @@ DeclareModule PBMap
  #PB_MAP_TILE_CLEANUP = #PB_EventType_FirstCustomValue + 3
  
  Declare InitPBMap(window)
+  Declare SetDebugLevel(level.i)
  Declare SetOption(Option.s, Value.s)
  Declare.s GetOption(Option.s)
  Declare LoadOptions(PreferencesFile.s = "PBMap.prefs")
@@ -124,7 +125,10 @@ Module PBMap
    URL.s
    CacheFile.s
    GetImageThread.i
-    RetryNb.i
+    Download.i
+    Time.i
+    Size.i
+    Mutex.i
  EndStructure
  
  Structure BoundingBox 
@@ -152,8 +156,9 @@ Module PBMap
  
  Structure ImgMemCach
    nImage.i
+    Size.i
    *Tile.Tile
-    TimeStackPosition.i
+    *TimeStackPtr
    Alpha.i
  EndStructure
  
@@ -197,6 +202,8 @@ Module PBMap
    ShowPointer.i
    TimerInterval.i
    MaxMemCache.i                                  ; in MiB
+    MaxThreads.i                                   ; Maximum simultaneous web loading threads
+    MaxDownloadSlots.i                             ; Maximum simultaneous download slots
    TileLifetime.i
    Verbose.i                                      ; Maximum debug informations
    Warning.i                                      ; Warning requesters
@@ -281,11 +288,16 @@ Module PBMap
    
    MemCache.TileMemCach                           ; Images in memory cache
    
+    ThreadsNB.i                                    ; Current web threads nb
+    
    Mode.i                                         ; User mode : 0 (default)->hand (moving map) and select markers, 1->hand, 2->select only (moving objects), 3->drawing (todo) 
    Redraw.i
    Dragging.i
    Dirty.i                                        ; To signal that drawing need a refresh
    
+    MemoryCacheAccessMutex.i                     ; Memorycache access variable mutual exclusion    
+    DownloadSlots.i                                ; Actual nb of used download slots
+    
    List TracksList.Tracks()                       ; To display a GPX track
    List Markers.Marker()                          ; To diplay marker
    EditMarker.l
@@ -300,7 +312,7 @@ Module PBMap
  ;-*** Global variables
  
  ;-Show debug infos 
-  Global MyDebugLevel = 3
+  Global MyDebugLevel = 5
  
  Global PBMap.PBMap, Null.i, NullPtrMem.i, *NullPtr = @NullPtrMem
  Global slash.s
@@ -344,9 +356,14 @@ Module PBMap
    EndIf
  EndProcedure  
    
+    ; Set the debug level allowing more or less debug infos
+  Procedure SetDebugLevel(level.i)
+    MyDebugLevel = level
+  EndProcedure 
+  
  ; Send debug infos to stdout (allowing mixed debug infos with curl or other libs)
  Procedure MyDebug(msg.s, DbgLevel = 0)
-    If PBMap\Options\Verbose And DbgLevel >= MyDebugLevel 
+    If PBMap\Options\Verbose And DbgLevel <= MyDebugLevel 
      PrintN(msg)
      ; Debug msg  
    EndIf
@@ -681,6 +698,10 @@ Module PBMap
        PBMap\Options\HDDCachePath = Value
      Case "maxmemcache"
        PBMap\Options\MaxMemCache = Val(Value)
+      Case "maxthreads"
+        PBMap\Options\MaxThreads = Val(Value)
+      Case "maxdownloadslots"
+        PBMap\Options\MaxDownloadSlots = Val(Value)
      Case "tilelifetime"
        PBMap\Options\TileLifetime =  Val(Value)
      Case "verbose"
@@ -748,6 +769,10 @@ Module PBMap
          ProcedureReturn \HDDCachePath
        Case "maxmemcache"
          ProcedureReturn StrU(\MaxMemCache)
+        Case "maxthreads"
+          ProcedureReturn StrU(\MaxThreads)
+        Case "maxdownloadslots"
+          ProcedureReturn StrU(\MaxDownloadSlots)
        Case "tilelifetime"
          ProcedureReturn StrU(\TileLifetime)  
        Case "verbose"
@@ -809,6 +834,8 @@ Module PBMap
      PreferenceGroup("OPTIONS")
      WritePreferenceInteger("WheelMouseRelative", \WheelMouseRelative)
      WritePreferenceInteger("MaxMemCache", \MaxMemCache)
+      WritePreferenceInteger("MaxThreads", \MaxThreads)
+      WritePreferenceInteger("MaxDownloadSlots", \MaxDownloadSlots)
      WritePreferenceInteger("TileLifetime", \TileLifetime)  
      WritePreferenceInteger("Verbose", \Verbose)
      WritePreferenceInteger("Warning", \Warning)
@@ -873,6 +900,8 @@ Module PBMap
      PreferenceGroup("OPTIONS")   
      \WheelMouseRelative = ReadPreferenceInteger("WheelMouseRelative", #True)
      \MaxMemCache        = ReadPreferenceInteger("MaxMemCache", 20480) ; 20 MiB, about 80 tiles in memory
+      \MaxThreads         = ReadPreferenceInteger("MaxThreads", 40)
+      \MaxDownloadSlots   = ReadPreferenceInteger("MaxDownloadSlots", 2)
      \TileLifetime       = ReadPreferenceInteger("TileLifetime", 1209600) ; about 2 weeks ;-1 = unlimited
      \Verbose            = ReadPreferenceInteger("Verbose", #False)
      \Warning            = ReadPreferenceInteger("Warning", #False)
@@ -891,7 +920,7 @@ Module PBMap
      \ColourFocus        = ReadPreferenceInteger("ColourFocus", RGBA(255, 255, 0, 255))
      \ColourSelected     = ReadPreferenceInteger("ColourSelected", RGBA(225, 225, 0, 255))
      \ColourTrackDefault = ReadPreferenceInteger("ColourTrackDefault", RGBA(0, 255, 0, 150))
-      \TimerInterval      = 20
+      \TimerInterval      = 12
      ClosePreferences()         
    EndWith
    SetOptions()
@@ -1021,51 +1050,73 @@ Module PBMap
    ProcedureReturn PBMap\Layers(Name)\Alpha
  EndProcedure
  
-  ;-*** These are threaded
+  ;-***
+  ; If cache size exceeds limit, try to delete the oldest tiles used (first in the time stack)
+  Procedure MemoryCacheManagement()
+    LockMutex(PBMap\MemoryCacheAccessMutex) ; Prevents thread to start or finish
+    Protected CacheSize = MapSize(PBMap\MemCache\Images()) * Pow(PBMap\TileSize, 2) * 4 ; Size of a tile = TileSize * TileSize * 4 bytes (RGBA) 
+    Protected CacheLimit = PBMap\Options\MaxMemCache * 1024
+    MyDebug("Cache size : " + Str(CacheSize/1024) + " / CacheLimit : " + Str(CacheLimit/1024), 5)
+    If CacheSize > CacheLimit    
+      MyDebug(" Cache full. Trying cache cleaning", 5)
+      ResetList(PBMap\MemCache\ImagesTimeStack())
+      ; Try to free half the cache memory (one pass)
+      While NextElement(PBMap\MemCache\ImagesTimeStack()) And CacheSize > (CacheLimit / 2) ; /2 = half
+        Protected CacheMapKey.s = PBMap\MemCache\ImagesTimeStack()\MapKey
+        ; Is the loading over
+        If PBMap\MemCache\Images(CacheMapKey)\Tile <= 0 ;TODO Should not verify this var directly
+          MyDebug("  Delete " + CacheMapKey, 5)
+          If PBMap\MemCache\Images(CacheMapKey)\nImage;IsImage(PBMap\MemCache\Images(CacheMapKey)\nImage)
+            FreeImage(PBMap\MemCache\Images(CacheMapKey)\nImage)
+            MyDebug("   and free image nb " + Str(PBMap\MemCache\Images(CacheMapKey)\nImage), 5)
+            PBMap\MemCache\Images(CacheMapKey)\nImage = 0
+          EndIf
+          DeleteMapElement(PBMap\MemCache\Images(), CacheMapKey)
+          DeleteElement(PBMap\MemCache\ImagesTimeStack(), 1)
+          ;           ElseIf PBMap\MemCache\Images(CacheMapKey)\Tile = 0 
+          ;             MyDebug("  Delete " + CacheMapKey, 5)
+          ;             DeleteMapElement(PBMap\MemCache\Images(), CacheMapKey)
+          ;             DeleteElement(PBMap\MemCache\ImagesTimeStack(), 1)
+          ;           ElseIf PBMap\MemCache\Images(CacheMapKey)\Tile > 0
+          ;             ; If the thread is running, try to abort the download
+          ;             If PBMap\MemCache\Images(CacheMapKey)\Tile\Download
+          ;               AbortHTTP(PBMap\MemCache\Images(CacheMapKey)\Tile\Download) ; Could lead to error
+          ;             EndIf
+        EndIf
+        CacheSize = MapSize(PBMap\MemCache\Images()) * Pow(PBMap\TileSize, 2) * 4 ; Size of a tile = TileSize * TileSize * 4 bytes (RGBA) 
+      Wend
+      MyDebug("  New cache size : " + Str(CacheSize/1024) + " / CacheLimit : " + Str(CacheLimit/1024), 5)      
+      If CacheSize > CacheLimit
+        MyDebug("  Cache cleaning unsuccessfull, can't add new tiles.", 5)
+      EndIf
+    EndIf
+    UnlockMutex(PBMap\MemoryCacheAccessMutex)
+  EndProcedure
  
  Procedure.i GetTileFromHDD(CacheFile.s)
-    Protected nImage.i, LifeTime.i, MaxLifeTime.i = PBMap\Options\TileLifetime
-    If FileSize(CacheFile) <> -1
-      ;Manage tile file lifetime
-      If MaxLifeTime <> -1
-        LifeTime = Date() - GetFileDate(CacheFile, #PB_Date_Modified) ;There's a bug with #PB_Date_Created
-        If LifeTime > MaxLifeTime
-          MyDebug("Deleting too old (" + StrU(LifeTime) + " secs) " + CacheFile, 3)
-          DeleteFile(CacheFile)
-          ProcedureReturn -1
-        EndIf
-      EndIf
-      ;Everything is OK, load the file
+    Protected nImage.i, LifeTime.i, MaxLifeTime.i
+      ; Everything is OK, loads the file
      nImage = LoadImage(#PB_Any, CacheFile)
-      If IsImage(nImage)
+      If nImage
        MyDebug(" Success loading " + CacheFile + " as nImage " + Str(nImage), 3)
        ProcedureReturn nImage  
      Else
        MyDebug(" Failed loading " + CacheFile + " as nImage " + Str(nImage) + " -> not an image !", 3)
+        If DeleteFile(CacheFile)
          MyDebug("  Deleting faulty image file  " + CacheFile, 3)
-        DeleteFile(CacheFile)
-      EndIf
        Else
-      MyDebug("Failed loading " + CacheFile + " -> Size <= 0", 3)
+          MyDebug("  Can't delete faulty image file  " + CacheFile, 3)
        EndIf
-    ProcedureReturn -1
+      EndIf
+    ProcedureReturn #False
  EndProcedure
  
-  Procedure.i GetTileFromWeb(TileURL.s, CacheFile.s)
-    Protected *Buffer
-    Protected nImage.i = -1
-    Protected FileSize.i, timg
-    FileSize = ReceiveHTTPFile(TileURL, CacheFile)
-    If FileSize > 0
-      MyDebug("Loaded from web " + TileURL + " as CacheFile " + CacheFile, 3)
-      nImage = GetTileFromHDD(CacheFile)
-    Else
-      MyDebug("Problem loading from web " + TileURL + " as CacheFile " + CacheFile, 3)
-    EndIf
-    ; **** IMPORTANT NOTICE (please not remove)
-    ; I'm (djes) now using Curl (actually, just normal pb) only, as this original catchimage/saveimage method is a double operation (uncompress/recompress PNG)
+  ; **** OLD IMPORTANT NOTICE (please not remove)
+  ; This original catchimage/saveimage method is a double operation (uncompress/recompress PNG)
  ; and is modifying the original PNG image which could lead to PNG error (Idle has spent hours debunking the 1 bit PNG bug)
-    ; More than that, the original Purebasic Receive library is still not Proxy enabled.
+  ; Protected *Buffer
+  ; Protected nImage.i = -1
+  ; Protected timg
  ; *Buffer = ReceiveHTTPMemory(TileURL)  ; TODO to thread by using #PB_HTTP_Asynchronous
  ; If *Buffer
  ; nImage = CatchImage(#PB_Any, *Buffer, MemorySize(*Buffer))
@@ -1084,106 +1135,175 @@ Module PBMap
  ; MyDebug(" Problem loading from web " + TileURL, 3)
  ; EndIf
  ; ****
-    ProcedureReturn nImage
-  EndProcedure
+  
+  ;-*** These are threaded
+  
+  Threaded Progress = 0, Quit = #False
  
  Procedure GetImageThread(*Tile.Tile)    
-    Protected nImage.i = -1
+    LockMutex(PBMap\MemoryCacheAccessMutex)
+    MyDebug("Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + " starting for image " + *Tile\CacheFile, 5)
+    ; If MemoryCache is currently being cleaned, abort
+;     If PBMap\MemoryCacheAccessNB = -1
+;       MyDebug(" Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + "  for image " + *Tile\CacheFile + " canceled because of cleaning.", 5)
+;       *Tile\Size = 0 ; \Size = 0 signals that the download has failed
+;       PostEvent(#PB_Event_Gadget, PBMap\Window, PBmap\Gadget, #PB_MAP_TILE_CLEANUP, *Tile) ; To free memory outside the thread
+;       UnlockMutex(PBMap\MemoryCacheAccessMutex)
+;       ProcedureReturn
+;     EndIf
+    ; We're accessing MemoryCache
+    UnlockMutex(PBMap\MemoryCacheAccessMutex)
+    *Tile\Size = 0
+    *Tile\Download = ReceiveHTTPFile(*Tile\URL, *Tile\CacheFile, #PB_HTTP_Asynchronous)
+    If *Tile\Download
      Repeat
-      nImage = GetTileFromWeb(*Tile\URL, *Tile\CacheFile)
-      If nImage <> -1
-        MyDebug("Image key : " + *Tile\key + " web image loaded", 3)
-        *Tile\RetryNb = 0
-      Else 
-        MyDebug("Image key : " + *Tile\key + " web image not correctly loaded, will retry in 2 secs", 3)
-        Delay(2000)
-        *Tile\RetryNb - 1
+        Progress = HTTPProgress(*Tile\Download)
+        Select Progress
+          Case #PB_Http_Success
+            *Tile\Size = FinishHTTP(*Tile\Download) ; \Size signals that the download is OK
+            MyDebug(" Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + " for image " + *Tile\CacheFile + " finished. Size : " + Str(*Tile\Size), 5)
+            Quit = #True
+          Case #PB_Http_Failed
+            FinishHTTP(*Tile\Download)
+            *Tile\Size = 0 ; \Size = 0 signals that the download has failed
+            MyDebug(" Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + "  for image " + *Tile\CacheFile + " failed.", 5)
+            Quit = #True
+          Case #PB_Http_Aborted
+            FinishHTTP(*Tile\Download)
+            *Tile\Size = 0 ; \Size = 0 signals that the download has failed
+            MyDebug(" Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + "  for image " + *Tile\CacheFile + " aborted.", 5)
+            Quit = #True
+          Default
+            MyDebug(" Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + "  for image " + *Tile\CacheFile + " downloading " + Str(Progress) + " bytes", 5)
+            If ElapsedMilliseconds() - *Tile\Time > 10000
+              MyDebug(" Thread nb " + Str(*Tile\GetImageThread) + " " + *Tile\key + "  for image " + *Tile\CacheFile + " canceled after 10 seconds.", 5)
+              AbortHTTP(*Tile\Download)
            EndIf
-    Until *Tile\RetryNb <= 0
-    *Tile\nImage = nImage
-    *Tile\RetryNb = -2 ;End of the thread    
+        EndSelect
+        Delay(200) ; Frees CPU
+      Until Quit
+    EndIf
+    ; End of the memory cache access
+    LockMutex(PBMap\MemoryCacheAccessMutex)
    PostEvent(#PB_Event_Gadget, PBMap\Window, PBmap\Gadget, #PB_MAP_TILE_CLEANUP, *Tile) ; To free memory outside the thread
+    UnlockMutex(PBMap\MemoryCacheAccessMutex)
  EndProcedure
+  
  ;-***
  
  Procedure.i GetTile(key.s, URL.s, CacheFile.s)
-    ; Try to find the tile in memory cache. If not found, add it, try to load it from the 
-    ; HDD, or launch a loading thread, and try again on the next drawing loop.
-    Protected img.i = -1
+    ; MemoryCache access management
+    LockMutex(PBMap\MemoryCacheAccessMutex)
+    ; Try to find the tile in memory cache
    Protected *timg.ImgMemCach = FindMapElement(PBMap\MemCache\Images(), key)
    If *timg
-      MyDebug("Key : " + key + " found in memory cache", 3)
-      img = *timg\nImage
-      If img <> -1
-        MyDebug("Image : " + img + " found in memory cache", 3)
+      MyDebug("Key : " + key + " found in memory cache", 4)
+      ; Is the associated image already been loaded in memory ?
+      If *timg\nImage
+        ; Yes, returns the image's nb
+        MyDebug(" as image " + *timg\nImage, 4)
        ; *** Cache management
-        ; Move the newly used element to the last position of the time stack
-        SelectElement(PBMap\MemCache\ImagesTimeStack(), *timg\TimeStackPosition)
+        ; Retrieves the image in the time stack, push it to the end (to say it's the lastly used)
+        ChangeCurrentElement(PBMap\MemCache\ImagesTimeStack(), *timg\TimeStackPtr)
        MoveElement(PBMap\MemCache\ImagesTimeStack(), #PB_List_Last)
+        ; *timg\TimeStackPtr = LastElement(PBMap\MemCache\ImagesTimeStack())
        ; ***
+        UnlockMutex(PBMap\MemoryCacheAccessMutex)
        ProcedureReturn *timg
+      Else
+        ; No, try to load it from HD (see below)
+        MyDebug(" but not the image.", 4)
      EndIf
    Else
-      ;PushMapPosition(PBMap\MemCache\Images())
-      ;*** Cache management
-      ; if cache size exceeds limit, try to delete the oldest tile used (first in the list)
-      Protected CacheSize = MapSize(PBMap\MemCache\Images()) * Pow(PBMap\TileSize, 2) * 4 ; Size of a tile = TileSize * TileSize * 4 bytes (RGBA) 
-      Protected CacheLimit = PBMap\Options\MaxMemCache * 1024
-      MyDebug("Cache size : " + Str(CacheSize/1024) + " / CacheLimit : " + Str(CacheLimit/1024), 4)
-      ResetList(PBMap\MemCache\ImagesTimeStack())
-      While NextElement(PBMap\MemCache\ImagesTimeStack()) And CacheSize > CacheLimit   
-        Protected CacheMapKey.s = PBMap\MemCache\ImagesTimeStack()\MapKey
-        Protected Image = PBMap\MemCache\Images(CacheMapKey)\nImage
-        If IsImage(Image) ; Check if the image is valid (is a loading thread running ?)
-          FreeImage(Image)
-          MyDebug("Delete " + CacheMapKey + " As image nb " + Str(Image), 4)
-          DeleteMapElement(PBMap\MemCache\Images(), CacheMapKey)
-          DeleteElement(PBMap\MemCache\ImagesTimeStack())
-          CacheSize = MapSize(PBMap\MemCache\Images()) * Pow(PBMap\TileSize, 2) * 4 ; Size of a tile = TileSize * TileSize * 4 bytes (RGBA) 
+      ; The tile has not been found in the cache, so creates a new cache element 
+      *timg = AddMapElement(PBMap\MemCache\Images(), key)
+      If *timg = 0
+        MyDebug("  Can't add a new cache element.", 4)
+        UnlockMutex(PBMap\MemoryCacheAccessMutex)
+        ProcedureReturn #False
      EndIf
-      Wend
+      ; add a new time stack element at the End     
      LastElement(PBMap\MemCache\ImagesTimeStack())
-      ;PopMapPosition(PBMap\MemCache\Images())
-      AddMapElement(PBMap\MemCache\Images(), key)
-      AddElement(PBMap\MemCache\ImagesTimeStack())
-      ;MoveElement(PBMap\MemCache\ImagesTimeStack(), #PB_List_Last)
+      ; Stores the time stack ptr   
+      *timg\TimeStackPtr = AddElement(PBMap\MemCache\ImagesTimeStack())
+      If *timg\TimeStackPtr = 0
+        MyDebug("  Can't add a new time stack element.", 4)
+        DeleteMapElement(PBMap\MemCache\Images())
+        UnlockMutex(PBMap\MemoryCacheAccessMutex)
+        ProcedureReturn #False
+      EndIf
+      ; Associates the time stack element to the cache element
      PBMap\MemCache\ImagesTimeStack()\MapKey = MapKey(PBMap\MemCache\Images())    
-      ;***
-      MyDebug("Key : " + key + " added in memory cache", 3)
-      *timg = PBMap\MemCache\Images()
-      *timg\nImage = -1
+      MyDebug("Key : " + key + " added in memory cache", 4)
    EndIf
-    If *timg\Tile = 0 ; Check if a loading thread is not running
-      MyDebug("Trying to load from HDD " + CacheFile, 3)
-      img = GetTileFromHDD(CacheFile.s)
-      If img <> -1
-        MyDebug("Key : " + key + " found on HDD", 3)
-        *timg\nImage = img
-        *timg\Alpha = 256
+    ; If there's no active download thread for this tile
+    If *timg\Tile <= 0        
+      ; Manage tile file lifetime, delete if too old
+      If PBMap\Options\TileLifetime <> -1 
+        If FileSize(CacheFile) > 0 ; Does the file exists ?
+          If Date() - GetFileDate(CacheFile, #PB_Date_Modified) > PBMap\Options\TileLifetime ; If Lifetime > MaxLifeTime ; There's a bug with #PB_Date_Created
+            If DeleteFile(CacheFile)
+              MyDebug("  Deleting too old image file  " + CacheFile, 3)
+            Else
+              MyDebug("  Can't delete too old image file  " + CacheFile, 3)
+              UnlockMutex(PBMap\MemoryCacheAccessMutex)
+              ProcedureReturn #False
+            EndIf
+          EndIf
+        EndIf
+      EndIf
+      ; Try To load it from HD
+      *timg\nImage = 0
+      *timg\Size = FileSize(CacheFile)
+      If *timg\Size > 0   
+        *timg\nImage = GetTileFromHDD(CacheFile.s)
+      Else
+        MyDebug(" Failed loading from HDD " + CacheFile + " -> Filesize = " + FileSize(CacheFile), 3)
+      EndIf
+      If *timg\nImage
+        ; Image found and loaded from HDD
+        *timg\Alpha = 0
+        UnlockMutex(PBMap\MemoryCacheAccessMutex)
        ProcedureReturn *timg
-      EndIf
-      MyDebug("Key : " + key + " not found on HDD", 3)
-      ;Launch a new thread
+      Else
+        ; If GetTileFromHDD failed, will load it (again?) from the web
+        If PBMap\ThreadsNB < PBMap\Options\MaxThreads
+          If PBMap\DownloadSlots < PBMap\Options\MaxDownloadSlots        
+            ; Launch a new web loading thread
+            PBMap\DownloadSlots + 1
            Protected *NewTile.Tile = AllocateMemory(SizeOf(Tile))
            If *NewTile
              With *NewTile 
-          *timg\Tile = *NewTile
-          *timg\Alpha = 0
-          ;*timg\nImage = -1    
                ; New tile parameters
                \key = key
                \URL = URL
                \CacheFile = CacheFile
-          \RetryNb = 5
-          \nImage = -1         
-          MyDebug(" Creating get image thread nb " + Str(\GetImageThread) + " to get " + CacheFile, 3)
+                \nImage = 0 
+                \Time = ElapsedMilliseconds()
                \GetImageThread = CreateThread(@GetImageThread(), *NewTile)
+                If \GetImageThread
+                  *timg\Tile = *NewTile ; There's now a loading thread
+                  *timg\Alpha = 0
+                  MyDebug(" Creating get image thread nb " + Str(\GetImageThread) + " to get " + CacheFile + " (key = " + key, 3)
+                  PBMap\ThreadsNB + 1
+                Else
+                  MyDebug(" Can't create get image thread to get " + CacheFile, 3)
+                  FreeMemory(*NewTile)
+                EndIf
              EndWith
            Else        
-        MyDebug(" Error, can't create a new tile loading thread", 3)
+              MyDebug(" Error, can't allocate memory for a new tile loading thread", 3)
+            EndIf            
+          Else
+            MyDebug(" Thread needed " + key + "  for image " + CacheFile + " canceled because no free download slot.", 5)
+          EndIf
+        Else
+          MyDebug(" Error, maximum threads nb reached", 3)
        EndIf
      EndIf
-    ProcedureReturn *timg 
+    EndIf
+    UnlockMutex(PBMap\MemoryCacheAccessMutex)
+    ProcedureReturn #False
  EndProcedure
  
  Procedure DrawTiles(*Drawing.DrawingParameters, LayerName.s)
@@ -1263,7 +1383,7 @@ Module PBMap
            EndSelect          
          EndWith
          *timg = GetTile(key, URL, CacheFile)
-          If *timg\nImage <> -1  
+          If *timg And *timg\nImage
            MovePathCursor(px, py)
            If *timg\Alpha <= 224
              DrawVectorImage(ImageID(*timg\nImage), *timg\Alpha * PBMap\Layers()\Alpha)
@@ -1737,23 +1857,23 @@ Module PBMap
    VectorFont(FontID(PBMap\Font), 16)
    VectorSourceColor(RGBA(0, 0, 0, 80))
    MovePathCursor(50, 50)
-    DrawVectorText(Str(MapSize(PBMap\MemCache\Images())))
+    DrawVectorText("Images in cache : " + Str(MapSize(PBMap\MemCache\Images())))
    MovePathCursor(50, 70)
    Protected ThreadCounter = 0
    ForEach PBMap\MemCache\Images()
-      If PBMap\MemCache\Images()\Tile <> 0
+      If PBMap\MemCache\Images()\Tile > 0
        If IsThread(PBMap\MemCache\Images()\Tile\GetImageThread)
          ThreadCounter + 1
        EndIf
      EndIf
    Next
-    DrawVectorText(Str(ThreadCounter))    
+    DrawVectorText("Threads nb : " + Str(ThreadCounter))    
    MovePathCursor(50, 90)
-    DrawVectorText(Str(PBMap\Zoom))
+    DrawVectorText("Zoom : " + Str(PBMap\Zoom))
    MovePathCursor(50, 110)
-    DrawVectorText(StrD(*Drawing\Bounds\NorthWest\Latitude) + "," + StrD(*Drawing\Bounds\NorthWest\Longitude))  
+    DrawVectorText("Lat-Lon 1 : " + StrD(*Drawing\Bounds\NorthWest\Latitude) + "," + StrD(*Drawing\Bounds\NorthWest\Longitude))  
    MovePathCursor(50, 130)
-    DrawVectorText(StrD(*Drawing\Bounds\SouthEast\Latitude) + "," + StrD(*Drawing\Bounds\SouthEast\Longitude))  
+    DrawVectorText("Lat-Lon 2 : " + StrD(*Drawing\Bounds\SouthEast\Latitude) + "," + StrD(*Drawing\Bounds\SouthEast\Longitude))  
  EndProcedure
  
  Procedure DrawOSMCopyright(*Drawing.DrawingParameters)
@@ -2113,11 +2233,11 @@ Module PBMap
      EndIf
    EndIf
    If DeleteDirectory(PBMap\Options\HDDCachePath, "", #PB_FileSystem_Recursive)
-      MyDebug("Cache in : " + PBMap\Options\HDDCachePath + " cleared")
+      MyDebug("Cache in : " + PBMap\Options\HDDCachePath + " cleared", 3)
      CreateDirectoryEx(PBMap\Options\HDDCachePath)
      ProcedureReturn #True
    Else
-      MyDebug("Can't clear cache in " + PBMap\Options\HDDCachePath)
+      MyDebug("Can't clear cache in " + PBMap\Options\HDDCachePath, 3)
      ProcedureReturn #False
    EndIf
  EndProcedure
@@ -2221,7 +2341,7 @@ Module PBMap
      Case #PB_EventType_LeftButtonDown
        ; LatLon2Pixel(@PBMap\GeographicCoordinates, @PBMap\PixelCoordinates, PBMap\Zoom)
        PBMap\Dragging = #True
-        ;Mem cursor Coord
+        ; Memorize cursor Coord
        PBMap\MoveStartingPoint\x = CanvasMouseX
        PBMap\MoveStartingPoint\y = CanvasMouseY
        ; Clip MouseX to the map range (in X, the map is infinite)
@@ -2339,20 +2459,27 @@ Module PBMap
        PBMap\Dragging = #False
        PBMap\Redraw = #True
      Case #PB_MAP_REDRAW
-        Debug "Redraw"
        PBMap\Redraw = #True
      Case #PB_MAP_RETRY
-        Debug "Reload"
        PBMap\Redraw = #True
+        ;- Tile web loading thread cleanup 
+        ; After a Web tile loading thread, clean the tile structure memory, see GetImageThread()
      Case #PB_MAP_TILE_CLEANUP
        *Tile = EventData() 
        key = *Tile\key           
-        ;After a Web tile loading thread, clean the tile structure memory and set the image nb in the cache
-        ;avoid to have threads accessing vars (and avoid mutex), see GetImageThread()
-        Protected timg = PBMap\MemCache\Images(key)\Tile\nImage ;Get this new tile image nb
-        PBMap\MemCache\Images(key)\nImage = timg                ;store it in the cache using the key
-        FreeMemory(PBMap\MemCache\Images(key)\Tile)             ;free the data needed for the thread
-        PBMap\MemCache\Images(key)\Tile = 0                     ;clear the data ptr
+        *Tile\Download = 0
+        If FindMapElement(PBMap\MemCache\Images(), key) <> 0
+          ; If the map element has not been deleted during the thread lifetime (should not occur)
+          PBMap\MemCache\Images(key)\Tile = *Tile\Size
+          If *Tile\Size
+            PBMap\MemCache\Images(key)\Tile = -1 ; Web loading thread has finished successfully
+          Else
+            PBMap\MemCache\Images(key)\Tile = 0
+          EndIf
+        EndIf
+        FreeMemory(*Tile)                                       ; Frees the data needed for the thread (*tile=PBMap\MemCache\Images(key)\Tile)
+        PBMap\ThreadsNB - 1
+        PBMap\DownloadSlots - 1
        PBMap\Redraw = #True
    EndSelect
  EndProcedure
@@ -2360,6 +2487,7 @@ Module PBMap
  ; Redraws at regular intervals
  Procedure TimerEvents()
    If EventTimer() = PBMap\Timer And (PBMap\Redraw Or PBMap\Dirty)
+      MemoryCacheManagement()
      Drawing()
    EndIf    
  EndProcedure 
@@ -2391,9 +2519,8 @@ Module PBMap
    Protected TimeCounter = ElapsedMilliseconds()
    Repeat
      ForEach PBMap\MemCache\Images()
-        If PBMap\MemCache\Images()\Tile <> 0         
+        If PBMap\MemCache\Images()\Tile > 0
          If IsThread(PBMap\MemCache\Images()\Tile\GetImageThread)
-            PBMap\MemCache\Images()\Tile\RetryNb = 0
            If ElapsedMilliseconds() - TimeCounter > 2000
              ; Should not occur
              KillThread(PBMap\MemCache\Images()\Tile\GetImageThread)
@@ -2411,17 +2538,24 @@ Module PBMap
  EndProcedure
  
  Procedure InitPBMap(Window)
+    With PBMap
      Protected Result.i
-    PBMap\ZoomMin = 1
-    PBMap\ZoomMax = 18
-    PBMap\Dragging = #False
-    PBMap\TileSize = 256
-    PBMap\Dirty = #False
-    PBMap\EditMarker = #False
-    PBMap\Font = LoadFont(#PB_Any, "Arial", 20, #PB_Font_Bold)
-    PBMap\Window = Window
-    PBMap\Timer = 1
-    PBMap\Mode = #MODE_DEFAULT
+      \ZoomMin = 1
+      \ZoomMax = 18
+      \Dragging = #False
+      \TileSize = 256
+      \Dirty = #False
+      \EditMarker = #False
+      \Font = LoadFont(#PB_Any, "Arial", 20, #PB_Font_Bold)
+      \Window = Window
+      \Timer = 1
+      \Mode = #MODE_DEFAULT
+      \MemoryCacheAccessMutex = CreateMutex() 
+      If \MemoryCacheAccessMutex = #False
+        MyDebug("Cannot create a mutex", 0)
+        End
+      EndIf
+    EndWith
    LoadOptions()
    TechnicalImagesCreation()
    SetLocation(0, 0)
@@ -2592,9 +2726,10 @@ CompilerIf #PB_Compiler_IsMainFile
    
    ; Our main gadget
    PBMap::InitPBMap(#Window_0)
-    PBMap::SetOption("ShowDegrees", "0") : Degrees = 0
-    PBMap::SetOption("ShowDebugInfos", "0")
-    PBMap::SetOption("Verbose", "0")
+    PBMap::SetOption("ShowDegrees", "1") : Degrees = 0
+    PBMap::SetOption("ShowDebugInfos", "1")
+    PBMap::SetDebugLevel(5)
+    PBMap::SetOption("Verbose", "1")
    PBMap::SetOption("ShowScale", "1")    
    PBMap::SetOption("Warning", "1")
    PBMap::SetOption("ShowMarkersLegend", "1")
@@ -2737,8 +2872,10 @@ CompilerIf #PB_Compiler_IsMainFile
 CompilerEndIf

 ; IDE Options = PureBasic 5.60 (Windows - x64)
-; CursorPosition = 2691
-; FirstLine = 2684
+; CursorPosition = 2552
+; FirstLine = 2548
 ; Folding = -------------------
 ; EnableThread
 ; EnableXP
+; CompileSourceDirectory
+; DisablePurifier = 1,1,1,1
--- a/README.md
+++ b/README.md
@@ -17,3 +17,4 @@ Thyphoon
 djes
 Idle
 Progi1984
+yves86