third_party/tcmalloc/chromium/src/tests/tcmalloc_large_unittest.cc

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  29
  30 // ---
  31 // Author: Michael Chastain
  32 //
  33 // This is a unit test for large allocations in malloc and friends.
  34 // "Large" means "so large that they overflow the address space".
  35 // For 32 bits, this means allocations near 2^32 bytes and 2^31 bytes.
  36 // For 64 bits, this means allocations near 2^64 bytes and 2^63 bytes.
  37
  38 #include <stddef.h>                     // for size_t, NULL
  39 #include <stdlib.h>                     // for malloc, free, realloc
  40 #include <stdio.h>
  41 #include <set>                          // for set, etc
  42
  43 #include "base/logging.h"               // for operator<<, CHECK, etc
  44
  45 using std::set;
  46
  47 // Alloc a size that should always fail.
  48
  49 void TryAllocExpectFail(size_t size) {
  50   void* p1 = malloc(size);
  51   CHECK(p1 == NULL);
  52
  53   void* p2 = malloc(1);
  54   CHECK(p2 != NULL);
  55
  56   void* p3 = realloc(p2, size);
  57   CHECK(p3 == NULL);
  58
  59   free(p2);
  60 }
  61
  62 // Alloc a size that might work and might fail.
  63 // If it does work, touch some pages.
  64
  65 void TryAllocMightFail(size_t size) {
  66   unsigned char* p = static_cast<unsigned char*>(malloc(size));
  67   if ( p != NULL ) {
  68     unsigned char volatile* vp = p;  // prevent optimizations
  69     static const size_t kPoints = 1024;
  70
  71     for ( size_t i = 0; i < kPoints; ++i ) {
  72       vp[i * (size / kPoints)] = static_cast<unsigned char>(i);
  73     }
  74
  75     for ( size_t i = 0; i < kPoints; ++i ) {
  76       CHECK(vp[i * (size / kPoints)] == static_cast<unsigned char>(i));
  77     }
  78
  79     vp[size-1] = 'M';
  80     CHECK(vp[size-1] == 'M');
  81   }
  82
  83   free(p);
  84 }
  85
  86 int main (int argc, char** argv) {
  87   // Allocate some 0-byte objects.  They better be unique.
  88   // 0 bytes is not large but it exercises some paths related to
  89   // large-allocation code.
  90   {
  91     static const int kZeroTimes = 1024;
  92     printf("Test malloc(0) x %d\n", kZeroTimes);
  93     set<char*> p_set;
  94     for ( int i = 0; i < kZeroTimes; ++i ) {
  95       char* p = new char;
  96       CHECK(p != NULL);
  97       CHECK(p_set.find(p) == p_set.end());
  98       p_set.insert(p_set.end(), p);
  99     }
 100     // Just leak the memory.
 101   }
 102
 103   // Grab some memory so that some later allocations are guaranteed to fail.
 104   printf("Test small malloc\n");
 105   void* p_small = malloc(4*1048576);
 106   CHECK(p_small != NULL);
 107
 108   // Test sizes up near the maximum size_t.
 109   // These allocations test the wrap-around code.
 110   printf("Test malloc(0 - N)\n");
 111   const size_t zero = 0;
 112   static const size_t kMinusNTimes = 16384;
 113   for ( size_t i = 1; i < kMinusNTimes; ++i ) {
 114     TryAllocExpectFail(zero - i);
 115   }
 116
 117   // Test sizes a bit smaller.
 118   // The small malloc above guarantees that all these return NULL.
 119   printf("Test malloc(0 - 1048576 - N)\n");
 120   static const size_t kMinusMBMinusNTimes = 16384;
 121   for ( size_t i = 0; i < kMinusMBMinusNTimes; ++i) {
 122     TryAllocExpectFail(zero - 1048576 - i);
 123   }
 124
 125   // Test sizes at half of size_t.
 126   // These might or might not fail to allocate.
 127   printf("Test malloc(max/2 +- N)\n");
 128   static const size_t kHalfPlusMinusTimes = 64;
 129   const size_t half = (zero - 2) / 2 + 1;
 130   for ( size_t i = 0; i < kHalfPlusMinusTimes; ++i) {
 131     TryAllocMightFail(half - i);
 132     TryAllocMightFail(half + i);
 133   }
 134
 135   printf("PASS\n");
 136   return 0;
 137 }