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1 // Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of "Eclipse Public License v1.0" |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Contributors: |
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12 // |
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13 // Description: |
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14 // Maintains a free queue of single size RMBuf's on behalf of CMBufPoolManager |
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15 // |
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16 // |
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17 |
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18 /** |
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19 @file |
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20 @internalComponent |
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21 */ |
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22 |
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23 |
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24 |
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25 #include "MBufPoolChain.h" |
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26 #include "MBufPool.h" |
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27 #include "MBufPoolManager.h" |
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28 #include "commsbufpool.h" |
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29 |
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30 |
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31 CMBufPoolChain::CMBufPoolChain(TInt aMBufSize, TInt aInitialAllocation, TInt aMinGrowth, TInt aGrowthThreshold, TInt aPoolCeiling, CMBufPoolManager& aMBufPoolManager) |
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32 : CCommsBufPool(aMBufPoolManager.Manager(), aMBufSize), |
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33 iLenFree(0), |
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34 iLenTotal(0), |
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35 iInitialAllocation(aInitialAllocation), |
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36 iMinGrowth(aMinGrowth), |
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37 iGrowthThreshold(aGrowthThreshold), |
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38 iSignalled(EFalse), |
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39 iNumMBufsToAdd(0), |
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40 iNoMoreSpace(0), |
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41 iLastGrowth(0), |
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42 iMaxGrowthAttempt(0), |
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43 iDbgPoolLimit(0), |
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44 iPoolCeiling(aPoolCeiling), |
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45 iMBufPoolManager(aMBufPoolManager) |
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46 { |
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47 } |
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48 CMBufPoolChain::CMBufPoolChain(TInt aMBufSize, CMBufPoolManager& aMBufPoolManager) |
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49 : CCommsBufPool(aMBufPoolManager.Manager(), aMBufSize), |
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50 iInitialAllocation(0), |
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51 iMBufPoolManager(aMBufPoolManager) |
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52 { |
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53 |
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54 } |
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55 |
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56 CMBufPoolChain* CMBufPoolChain::NewL(TInt aMBufSize, TInt aInitialAllocation, TInt aMinGrowth, TInt aGrowthThreshold, TInt aPoolCeiling, CMBufPoolManager& aMBufPoolManager) |
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57 { |
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58 CMBufPoolChain* self = new(ELeave)CMBufPoolChain(aMBufSize, aInitialAllocation, aMinGrowth, aGrowthThreshold, aPoolCeiling, aMBufPoolManager); |
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59 CleanupStack::PushL(self); |
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60 self->ConstructL(); |
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61 CleanupStack::Pop(); // self |
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62 return self; |
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63 } |
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64 |
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65 void CMBufPoolChain::ConstructL() |
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66 { |
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67 iFreeMBufs.Init(); |
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68 User::LeaveIfError(iLockFreeList.CreateLocal()); |
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69 iPools.Reset(); |
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70 iPools.SetOffset(_FOFF(CMBufPool, iLink)); |
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71 } |
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72 |
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73 CMBufPoolChain::~CMBufPoolChain() |
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74 { |
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75 iLockFreeList.Close(); |
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76 } |
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77 |
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78 |
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79 |
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80 // get the growth amount |
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81 TInt CMBufPoolChain::GrowthSize(TInt aSize) |
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82 { |
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83 // small request so grow by minimum size |
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84 if (aSize < iMinGrowth) |
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85 { |
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86 return iMinGrowth; |
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87 } |
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88 |
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89 // Have we tried as big as this in the past? |
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90 if ( (iMaxGrowthAttempt > 0) && (aSize >= iMaxGrowthAttempt) ) |
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91 { |
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92 // try smaller size again |
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93 aSize = iMaxGrowthAttempt; |
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94 } |
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95 |
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96 // Attempt to grow the pool by requested amount |
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97 if (!iNoMoreSpace) |
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98 { |
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99 return aSize; |
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100 } |
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101 |
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102 // Last growth attempt failed so check if its worth |
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103 // trying again |
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104 if ( iLastGrowth < (iMinGrowth + 2)) |
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105 { |
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106 return 0; |
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107 } |
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108 |
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109 // Last growth attempt failed so lets try a smaller |
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110 iMaxGrowthAttempt = iMinGrowth + (iLastGrowth - iMinGrowth) / 2; |
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111 |
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112 return iMaxGrowthAttempt; |
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113 } |
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114 |
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115 // merge new pool into the pool chain |
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116 void CMBufPoolChain::ExtendFreeList(CMBufPool* aPool) |
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117 { |
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118 // The caller must already have acquired the freelist lock |
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119 // - justification; |
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120 // a. limitation in RWorkerLock's RFastLock which does not support nested requests by the same thread without hanging the thread |
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121 // b. performance is adversely affected by continuoulsy locking & releasing the lock by the caller, refer ::Alloc |
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122 // - assumption is checked for debug builds, but not for release builds as it is too expensive & indicates a serous coding error that |
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123 // could/should of been fixed within a debug build anyhow |
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124 __ASSERT_DEBUG(iLockFreeList.IsOwned(), CMBufManager::Panic(EMBuf_FreeLockNotOwned)); |
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125 |
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126 iFreeMBufs.Append(aPool->MBufQ()); |
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127 iLenFree += aPool->Count() * iBufSize; |
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128 iLenTotal += aPool->Count() * iBufSize; |
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129 } |
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130 |
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131 // allocate a chain of MBufs from the pool chain |
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132 TInt CMBufPoolChain::Alloc(RMBufQ& aList, TInt aSize, TBool aIsAllocPool) |
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133 { |
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134 |
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135 // Lock the freelist so that the transfer of mbufs and statistics update is an atomic operation |
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136 iLockFreeList.Wait(); |
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137 |
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138 TInt transfered = iFreeMBufs.Transfer(aList, aSize, BufSize()); |
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139 iLenFree -= transfered; |
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140 |
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141 // If necessary gather data from the poolChain within the freelist lock to ensure integrity of statistics used |
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142 TInt preAllocationLength = 0; |
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143 if (aIsAllocPool) |
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144 { |
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145 preAllocationLength = iGrowthThreshold - (iLenFree/iBufSize); // determine in terms of number of mbufs. |
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146 } |
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147 |
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148 // adjust the growth if necessary |
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149 TInt growth = 0; |
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150 if (preAllocationLength >= 0) |
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151 { |
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152 growth = GrowthSize(preAllocationLength); |
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153 } |
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154 |
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155 // Now free the freelist lock |
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156 iLockFreeList.Signal(); |
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157 |
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158 // check if the growth threshold trigger has been exceeded, and if so perform a background pool (pre)allocation |
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159 if (aIsAllocPool) |
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160 { |
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161 if (preAllocationLength >= 0) |
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162 { |
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163 // a failed background (pre)allocation shall not error the user since they shouldn't know (and hence care), thus |
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164 // the return code is only used to avoid a perpetual loop |
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165 if (growth > 0) |
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166 { |
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167 if (KErrNoMBufs == iMBufPoolManager.AllocPool(*this, growth, EFalse)) |
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168 { |
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169 iMaxGrowthAttempt = growth; |
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170 } |
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171 } |
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172 } |
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173 } |
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174 return transfered; |
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175 } |
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176 |
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177 // compare function to find the suitable pool chain |
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178 TInt CMBufPoolChain::Compare(const TInt* aMBufSize, const CMBufPoolChain& aRHSPoolChain) |
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179 { |
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180 if (*aMBufSize < aRHSPoolChain.BufSize()) |
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181 { |
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182 return -1; |
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183 } |
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184 else if (*aMBufSize > aRHSPoolChain.BufSize()) |
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185 { |
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186 return 1; |
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187 } |
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188 return 0; |
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189 } |
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190 |
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191 TInt CMBufPoolChain::Compare(const CMBufPoolChain& aLHSPoolChain, const CMBufPoolChain& aRHSPoolChain) |
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192 { |
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193 return Compare((TInt*)&(aLHSPoolChain.iBufSize), aRHSPoolChain); |
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194 } |
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195 |
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196 CMBufPoolManager& CMBufPoolChain::MBufPoolManager() |
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197 { |
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198 return iMBufPoolManager; |
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199 } |
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200 |
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201 TBool CMBufPoolChain::CanExtend() const |
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202 { |
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203 return iLenTotal < iPoolCeiling; |
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204 } |
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205 |
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206 TInt CMBufPoolChain::ExtendSize() const |
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207 { |
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208 if(iLenTotal == 0) |
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209 { |
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210 // Always return the initial allocation value if we haven't allocated anything yet. |
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211 return iInitialAllocation; |
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212 } |
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213 |
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214 |
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215 TInt toGrow = (iPoolCeiling - iLenTotal)/iBufSize; |
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216 return (toGrow < iMinGrowth) ? toGrow : iMinGrowth ; |
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217 } |
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218 |
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219 TBool CMBufPoolChain::HonourPoolCeiling() const |
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220 { |
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221 return iPoolCeiling != KErrNotFound; |
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222 } |
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223 |
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224 |