8150460: (linux|bsd|aix)_close.c: file descriptor table may become large or may not work at all

Reviewed-by: dsamersoff, rriggs

src/aix/native/java/net/aix_close.c

@@ -39,6 +39,9 @@
  * (see aix_close_init).
  *
  */
+
+#include <assert.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
@@ -76,10 +79,35 @@ typedef struct {
 static int sigWakeup = (SIGRTMAX - 1);
 
 /*
- * The fd table and the number of file descriptors
+ * fdTable holds one entry per file descriptor, up to a certain
+ * maximum.
+ * Theoretically, the number of possible file descriptors can get
+ * large, though usually it does not. Entries for small value file
+ * descriptors are kept in a simple table, which covers most scenarios.
+ * Entries for large value file descriptors are kept in an overflow
+ * table, which is organized as a sparse two dimensional array whose
+ * slabs are allocated on demand. This covers all corner cases while
+ * keeping memory consumption reasonable.
+ */
+
+/* Base table for low value file descriptors */
+static fdEntry_t* fdTable = NULL;
+/* Maximum size of base table (in number of entries). */
+static const int fdTableMaxSize = 0x1000; /* 4K */
+/* Actual size of base table (in number of entries) */
+static int fdTableLen = 0;
+/* Max. theoretical number of file descriptors on system. */
+static int fdLimit = 0;
+
+/* Overflow table, should base table not be large enough. Organized as
+ *   an array of n slabs, each holding 64k entries.
  */
-static fdEntry_t *fdTable = NULL;
-static int fdCount = 0;
+static fdEntry_t** fdOverflowTable = NULL;
+/* Number of slabs in the overflow table */
+static int fdOverflowTableLen = 0;
+/* Number of entries in one slab */
+static const int fdOverflowTableSlabSize = 0x10000; /* 64k */
+pthread_mutex_t fdOverflowTableLock = PTHREAD_MUTEX_INITIALIZER;
 
 /*
  * Null signal handler
@@ -98,42 +126,42 @@ void aix_close_init() {
     struct rlimit nbr_files;
     sigset_t sigset;
     struct sigaction sa;
+    int i = 0;
 
-    /* Check already initialized */
-    if (fdCount > 0 && fdTable != NULL) {
-        return;
-    }
-
-    /*
-     * Allocate table based on the maximum number of
-     * file descriptors.
-     */
+    /* Determine the maximum number of possible file descriptors. */
     if (-1 == getrlimit(RLIMIT_NOFILE, &nbr_files)) {
         fprintf(stderr, "library initialization failed - "
                 "unable to get max # of allocated fds\n");
         abort();
     }
-    fdCount = nbr_files.rlim_max;
-    /*
-     * We have a conceptual problem here, when the number of files is
-     * unlimited. As a kind of workaround, we ensure the table is big
-     * enough for handle even a large number of files. Since SAP itself
-     * recommends a limit of 32000 files, we just use 64000 as 'infinity'.
-     */
-    if (nbr_files.rlim_max == RLIM_INFINITY) {
-        fdCount = 64000;
+    if (nbr_files.rlim_max != RLIM_INFINITY) {
+        fdLimit = nbr_files.rlim_max;
+    } else {
+        /* We just do not know. */
+        fdLimit = INT_MAX;
     }
-    fdTable = (fdEntry_t *)calloc(fdCount, sizeof(fdEntry_t));
+
+    /* Allocate table for low value file descriptors. */
+    fdTableLen = fdLimit < fdTableMaxSize ? fdLimit : fdTableMaxSize;
+    fdTable = (fdEntry_t*) calloc(fdTableLen, sizeof(fdEntry_t));
     if (fdTable == NULL) {
         fprintf(stderr, "library initialization failed - "
                 "unable to allocate file descriptor table - out of memory");
         abort();
+    } else {
+        for (i = 0; i < fdTableLen; i ++) {
+            pthread_mutex_init(&fdTable[i].lock, NULL);
+        }
     }
 
-    {
-        int i;
-        for (i=0; i < fdCount; i++) {
-            pthread_mutex_init(&fdTable[i].lock, NULL);
+    /* Allocate overflow table, if needed */
+    if (fdLimit > fdTableMaxSize) {
+        fdOverflowTableLen = ((fdLimit - fdTableMaxSize) / fdOverflowTableSlabSize) + 1;
+        fdOverflowTable = (fdEntry_t**) calloc(fdOverflowTableLen, sizeof(fdEntry_t*));
+        if (fdOverflowTable == NULL) {
+            fprintf(stderr, "library initialization failed - "
+                    "unable to allocate file descriptor overflow table - out of memory");
+            abort();
         }
     }
 
@@ -151,17 +179,60 @@ void aix_close_init() {
 }
 
 /*
- * Return the fd table for this fd or NULL is fd out
- * of range.
+ * Return the fd table for this fd.
  */
 static inline fdEntry_t *getFdEntry(int fd)
 {
-    if (fd < 0 || fd >= fdCount) {
+    fdEntry_t* result = NULL;
+
+    if (fd < 0) {
         return NULL;
     }
-    return &fdTable[fd];
+
+    /* This should not happen. If it does, our assumption about
+     * max. fd value was wrong. */
+    assert(fd < fdLimit);
+
+    if (fd < fdTableMaxSize) {
+        /* fd is in base table. */
+        assert(fd < fdTableLen);
+        result = &fdTable[fd];
+    } else {
+        /* fd is in overflow table. */
+        const int indexInOverflowTable = fd - fdTableMaxSize;
+        const int rootindex = indexInOverflowTable / fdOverflowTableSlabSize;
+        const int slabindex = indexInOverflowTable % fdOverflowTableSlabSize;
+        fdEntry_t* slab = NULL;
+        assert(rootindex < fdOverflowTableLen);
+        assert(slabindex < fdOverflowTableSlabSize);
+        pthread_mutex_lock(&fdOverflowTableLock);
+        /* Allocate new slab in overflow table if needed */
+        if (fdOverflowTable[rootindex] == NULL) {
+            fdEntry_t* const newSlab =
+                (fdEntry_t*)calloc(fdOverflowTableSlabSize, sizeof(fdEntry_t));
+            if (newSlab == NULL) {
+                fprintf(stderr, "Unable to allocate file descriptor overflow"
+                        " table slab - out of memory");
+                pthread_mutex_unlock(&fdOverflowTableLock);
+                abort();
+            } else {
+                int i;
+                for (i = 0; i < fdOverflowTableSlabSize; i ++) {
+                    pthread_mutex_init(&newSlab[i].lock, NULL);
+                }
+                fdOverflowTable[rootindex] = newSlab;
+            }
+        }
+        pthread_mutex_unlock(&fdOverflowTableLock);
+        slab = fdOverflowTable[rootindex];
+        result = &slab[slabindex];
+    }
+
+    return result;
+
 }
 
+
 /*
  * Start a blocking operation :-
  *    Insert thread onto thread list for the fd.

src/solaris/native/java/net/bsd_close.c

@@ -23,6 +23,8 @@
  * questions.
  */
 
+#include <assert.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/param.h>
@@ -61,18 +63,35 @@ typedef struct {
 static int sigWakeup = SIGIO;
 
 /*
- * The fd table and the number of file descriptors
+ * fdTable holds one entry per file descriptor, up to a certain
+ * maximum.
+ * Theoretically, the number of possible file descriptors can get
+ * large, though usually it does not. Entries for small value file
+ * descriptors are kept in a simple table, which covers most scenarios.
+ * Entries for large value file descriptors are kept in an overflow
+ * table, which is organized as a sparse two dimensional array whose
+ * slabs are allocated on demand. This covers all corner cases while
+ * keeping memory consumption reasonable.
  */
-static fdEntry_t *fdTable;
-static int fdCount;
 
-/*
- * This limit applies if getlimit() returns unlimited.
- * Unfortunately, this means if someone wants a higher limit
- * then they have to set an explicit limit, higher than this,
- * which is probably counter-intuitive.
+/* Base table for low value file descriptors */
+static fdEntry_t* fdTable = NULL;
+/* Maximum size of base table (in number of entries). */
+static const int fdTableMaxSize = 0x1000; /* 4K */
+/* Actual size of base table (in number of entries) */
+static int fdTableLen = 0;
+/* Max. theoretical number of file descriptors on system. */
+static int fdLimit = 0;
+
+/* Overflow table, should base table not be large enough. Organized as
+ *   an array of n slabs, each holding 64k entries.
  */
-#define MAX_FD_COUNT 4096
+static fdEntry_t** fdOverflowTable = NULL;
+/* Number of slabs in the overflow table */
+static int fdOverflowTableLen = 0;
+/* Number of entries in one slab */
+static const int fdOverflowTableSlabSize = 0x10000; /* 64k */
+pthread_mutex_t fdOverflowTableLock = PTHREAD_MUTEX_INITIALIZER;
 
 /*
  * Null signal handler
@@ -88,26 +107,43 @@ static void __attribute((constructor)) init() {
     struct rlimit nbr_files;
     sigset_t sigset;
     struct sigaction sa;
-    int i;
+    int i = 0;
 
-    /*
-     * Allocate table based on the maximum number of
-     * file descriptors.
-     */
-    getrlimit(RLIMIT_NOFILE, &nbr_files);
-    if (nbr_files.rlim_max == RLIM_INFINITY) {
-        fdCount = MAX_FD_COUNT;
+    /* Determine the maximum number of possible file descriptors. */
+    if (-1 == getrlimit(RLIMIT_NOFILE, &nbr_files)) {
+        fprintf(stderr, "library initialization failed - "
+                "unable to get max # of allocated fds\n");
+        abort();
+    }
+    if (nbr_files.rlim_max != RLIM_INFINITY) {
+        fdLimit = nbr_files.rlim_max;
     } else {
-        fdCount = nbr_files.rlim_max;
+        /* We just do not know. */
+        fdLimit = INT_MAX;
     }
-    fdTable = (fdEntry_t *)calloc(fdCount, sizeof(fdEntry_t));
+
+    /* Allocate table for low value file descriptors. */
+    fdTableLen = fdLimit < fdTableMaxSize ? fdLimit : fdTableMaxSize;
+    fdTable = (fdEntry_t*) calloc(fdTableLen, sizeof(fdEntry_t));
     if (fdTable == NULL) {
         fprintf(stderr, "library initialization failed - "
                 "unable to allocate file descriptor table - out of memory");
         abort();
+    } else {
+        for (i = 0; i < fdTableLen; i ++) {
+            pthread_mutex_init(&fdTable[i].lock, NULL);
+        }
     }
-    for (i=0; i<fdCount; i++) {
-        pthread_mutex_init(&fdTable[i].lock, NULL);
+
+    /* Allocate overflow table, if needed */
+    if (fdLimit > fdTableMaxSize) {
+        fdOverflowTableLen = ((fdLimit - fdTableMaxSize) / fdOverflowTableSlabSize) + 1;
+        fdOverflowTable = (fdEntry_t**) calloc(fdOverflowTableLen, sizeof(fdEntry_t*));
+        if (fdOverflowTable == NULL) {
+            fprintf(stderr, "library initialization failed - "
+                    "unable to allocate file descriptor overflow table - out of memory");
+            abort();
+        }
     }
 
     /*
@@ -124,17 +160,60 @@ static void __attribute((constructor)) init() {
 }
 
 /*
- * Return the fd table for this fd or NULL is fd out
- * of range.
+ * Return the fd table for this fd.
  */
 static inline fdEntry_t *getFdEntry(int fd)
 {
-    if (fd < 0 || fd >= fdCount) {
+    fdEntry_t* result = NULL;
+
+    if (fd < 0) {
         return NULL;
     }
-    return &fdTable[fd];
+
+    /* This should not happen. If it does, our assumption about
+     * max. fd value was wrong. */
+    assert(fd < fdLimit);
+
+    if (fd < fdTableMaxSize) {
+        /* fd is in base table. */
+        assert(fd < fdTableLen);
+        result = &fdTable[fd];
+    } else {
+        /* fd is in overflow table. */
+        const int indexInOverflowTable = fd - fdTableMaxSize;
+        const int rootindex = indexInOverflowTable / fdOverflowTableSlabSize;
+        const int slabindex = indexInOverflowTable % fdOverflowTableSlabSize;
+        fdEntry_t* slab = NULL;
+        assert(rootindex < fdOverflowTableLen);
+        assert(slabindex < fdOverflowTableSlabSize);
+        pthread_mutex_lock(&fdOverflowTableLock);
+        /* Allocate new slab in overflow table if needed */
+        if (fdOverflowTable[rootindex] == NULL) {
+            fdEntry_t* const newSlab =
+                (fdEntry_t*)calloc(fdOverflowTableSlabSize, sizeof(fdEntry_t));
+            if (newSlab == NULL) {
+                fprintf(stderr, "Unable to allocate file descriptor overflow"
+                        " table slab - out of memory");
+                pthread_mutex_unlock(&fdOverflowTableLock);
+                abort();
+            } else {
+                int i;
+                for (i = 0; i < fdOverflowTableSlabSize; i ++) {
+                    pthread_mutex_init(&newSlab[i].lock, NULL);
+                }
+                fdOverflowTable[rootindex] = newSlab;
+            }
+        }
+        pthread_mutex_unlock(&fdOverflowTableLock);
+        slab = fdOverflowTable[rootindex];
+        result = &slab[slabindex];
+    }
+
+    return result;
+
 }
 
+
 /*
  * Start a blocking operation :-
  *    Insert thread onto thread list for the fd.

src/solaris/native/java/net/linux_close.c

@@ -23,6 +23,8 @@
  * questions.
  */
 
+#include <assert.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
@@ -59,10 +61,35 @@ typedef struct {
 static int sigWakeup = (__SIGRTMAX - 2);
 
 /*
- * The fd table and the number of file descriptors
+ * fdTable holds one entry per file descriptor, up to a certain
+ * maximum.
+ * Theoretically, the number of possible file descriptors can get
+ * large, though usually it does not. Entries for small value file
+ * descriptors are kept in a simple table, which covers most scenarios.
+ * Entries for large value file descriptors are kept in an overflow
+ * table, which is organized as a sparse two dimensional array whose
+ * slabs are allocated on demand. This covers all corner cases while
+ * keeping memory consumption reasonable.
  */
-static fdEntry_t *fdTable;
-static int fdCount;
+
+/* Base table for low value file descriptors */
+static fdEntry_t* fdTable = NULL;
+/* Maximum size of base table (in number of entries). */
+static const int fdTableMaxSize = 0x1000; /* 4K */
+/* Actual size of base table (in number of entries) */
+static int fdTableLen = 0;
+/* Max. theoretical number of file descriptors on system. */
+static int fdLimit = 0;
+
+/* Overflow table, should base table not be large enough. Organized as
+ *   an array of n slabs, each holding 64k entries.
+ */
+static fdEntry_t** fdOverflowTable = NULL;
+/* Number of slabs in the overflow table */
+static int fdOverflowTableLen = 0;
+/* Number of entries in one slab */
+static const int fdOverflowTableSlabSize = 0x10000; /* 64k */
+pthread_mutex_t fdOverflowTableLock = PTHREAD_MUTEX_INITIALIZER;
 
 /*
  * Null signal handler
@@ -78,18 +105,43 @@ static void __attribute((constructor)) init() {
     struct rlimit nbr_files;
     sigset_t sigset;
     struct sigaction sa;
+    int i = 0;
 
-    /*
-     * Allocate table based on the maximum number of
-     * file descriptors.
-     */
-    getrlimit(RLIMIT_NOFILE, &nbr_files);
-    fdCount = nbr_files.rlim_max;
-    fdTable = (fdEntry_t *)calloc(fdCount, sizeof(fdEntry_t));
+    /* Determine the maximum number of possible file descriptors. */
+    if (-1 == getrlimit(RLIMIT_NOFILE, &nbr_files)) {
+        fprintf(stderr, "library initialization failed - "
+                "unable to get max # of allocated fds\n");
+        abort();
+    }
+    if (nbr_files.rlim_max != RLIM_INFINITY) {
+        fdLimit = nbr_files.rlim_max;
+    } else {
+        /* We just do not know. */
+        fdLimit = INT_MAX;
+    }
+
+    /* Allocate table for low value file descriptors. */
+    fdTableLen = fdLimit < fdTableMaxSize ? fdLimit : fdTableMaxSize;
+    fdTable = (fdEntry_t*) calloc(fdTableLen, sizeof(fdEntry_t));
     if (fdTable == NULL) {
         fprintf(stderr, "library initialization failed - "
                 "unable to allocate file descriptor table - out of memory");
         abort();
+    } else {
+        for (i = 0; i < fdTableLen; i ++) {
+            pthread_mutex_init(&fdTable[i].lock, NULL);
+        }
+    }
+
+    /* Allocate overflow table, if needed */
+    if (fdLimit > fdTableMaxSize) {
+        fdOverflowTableLen = ((fdLimit - fdTableMaxSize) / fdOverflowTableSlabSize) + 1;
+        fdOverflowTable = (fdEntry_t**) calloc(fdOverflowTableLen, sizeof(fdEntry_t*));
+        if (fdOverflowTable == NULL) {
+            fprintf(stderr, "library initialization failed - "
+                    "unable to allocate file descriptor overflow table - out of memory");
+            abort();
+        }
     }
 
     /*
@@ -106,15 +158,57 @@ static void __attribute((constructor)) init() {
 }
 
 /*
- * Return the fd table for this fd or NULL is fd out
- * of range.
+ * Return the fd table for this fd.
  */
 static inline fdEntry_t *getFdEntry(int fd)
 {
-    if (fd < 0 || fd >= fdCount) {
+    fdEntry_t* result = NULL;
+
+    if (fd < 0) {
         return NULL;
     }
-    return &fdTable[fd];
+
+    /* This should not happen. If it does, our assumption about
+     * max. fd value was wrong. */
+    assert(fd < fdLimit);
+
+    if (fd < fdTableMaxSize) {
+        /* fd is in base table. */
+        assert(fd < fdTableLen);
+        result = &fdTable[fd];
+    } else {
+        /* fd is in overflow table. */
+        const int indexInOverflowTable = fd - fdTableMaxSize;
+        const int rootindex = indexInOverflowTable / fdOverflowTableSlabSize;
+        const int slabindex = indexInOverflowTable % fdOverflowTableSlabSize;
+        fdEntry_t* slab = NULL;
+        assert(rootindex < fdOverflowTableLen);
+        assert(slabindex < fdOverflowTableSlabSize);
+        pthread_mutex_lock(&fdOverflowTableLock);
+        /* Allocate new slab in overflow table if needed */
+        if (fdOverflowTable[rootindex] == NULL) {
+            fdEntry_t* const newSlab =
+                (fdEntry_t*)calloc(fdOverflowTableSlabSize, sizeof(fdEntry_t));
+            if (newSlab == NULL) {
+                fprintf(stderr, "Unable to allocate file descriptor overflow"
+                        " table slab - out of memory");
+                pthread_mutex_unlock(&fdOverflowTableLock);
+                abort();
+            } else {
+                int i;
+                for (i = 0; i < fdOverflowTableSlabSize; i ++) {
+                    pthread_mutex_init(&newSlab[i].lock, NULL);
+                }
+                fdOverflowTable[rootindex] = newSlab;
+            }
+        }
+        pthread_mutex_unlock(&fdOverflowTableLock);
+        slab = fdOverflowTable[rootindex];
+        result = &slab[slabindex];
+    }
+
+    return result;
+
 }
 
 /*