1 /*------------------------------------------------------------------------- 2 * 3 * jit.c 4 * Provider independent JIT infrastructure. 5 * 6 * Code related to loading JIT providers, redirecting calls into JIT providers 7 * and error handling. No code specific to a specific JIT implementation 8 * should end up here. 9 * 10 * 11 * Copyright (c) 2016-2019, PostgreSQL Global Development Group 12 * 13 * IDENTIFICATION 14 * src/backend/jit/jit.c 15 * 16 *------------------------------------------------------------------------- 17 */ 18 #include "postgres.h" 19 20 21 #include <sys/types.h> 22 #include <sys/stat.h> 23 #include <unistd.h> 24 25 26 #include "fmgr.h" 27 #include "executor/execExpr.h" 28 #include "jit/jit.h" 29 #include "miscadmin.h" 30 #include "utils/resowner_private.h" 31 #include "utils/fmgrprotos.h" 32 33 34 /* GUCs */ 35 bool jit_enabled = true; 36 char *jit_provider = NULL; 37 bool jit_debugging_support = false; 38 bool jit_dump_bitcode = false; 39 bool jit_expressions = true; 40 bool jit_profiling_support = false; 41 bool jit_tuple_deforming = true; 42 double jit_above_cost = 100000; 43 double jit_inline_above_cost = 500000; 44 double jit_optimize_above_cost = 500000; 45 46 static JitProviderCallbacks provider; 47 static bool provider_successfully_loaded = false; 48 static bool provider_failed_loading = false; 49 50 51 static bool provider_init(void); 52 static bool file_exists(const char *name); 53 54 55 /* 56 * SQL level function returning whether JIT is available in the current 57 * backend. Will attempt to load JIT provider if necessary. 58 */ 59 Datum 60 pg_jit_available(PG_FUNCTION_ARGS) 61 { 62 PG_RETURN_BOOL(provider_init()); 63 } 64 65 66 /* 67 * Return whether a JIT provider has successfully been loaded, caching the 68 * result. 69 */ 70 static bool 71 provider_init(void) 72 { 73 char path[MAXPGPATH]; 74 JitProviderInit init; 75 76 /* don't even try to load if not enabled */ 77 if (!jit_enabled) 78 return false; 79 80 /* 81 * Don't retry loading after failing - attempting to load JIT provider 82 * isn't cheap. 83 */ 84 if (provider_failed_loading) 85 return false; 86 if (provider_successfully_loaded) 87 return true; 88 89 /* 90 * Check whether shared library exists. We do that check before actually 91 * attempting to load the shared library (via load_external_function()), 92 * because that'd error out in case the shlib isn't available. 93 */ 94 snprintf(path, MAXPGPATH, "%s/%s%s", pkglib_path, jit_provider, DLSUFFIX); 95 elog(DEBUG1, "probing availability of JIT provider at %s", path); 96 if (!file_exists(path)) 97 { 98 elog(DEBUG1, 99 "provider not available, disabling JIT for current session"); 100 provider_failed_loading = true; 101 return false; 102 } 103 104 /* 105 * If loading functions fails, signal failure. We do so because 106 * load_external_function() might error out despite the above check if 107 * e.g. the library's dependencies aren't installed. We want to signal 108 * ERROR in that case, so the user is notified, but we don't want to 109 * continually retry. 110 */ 111 provider_failed_loading = true; 112 113 /* and initialize */ 114 init = (JitProviderInit) 115 load_external_function(path, "_PG_jit_provider_init", true, NULL); 116 init(&provider); 117 118 provider_successfully_loaded = true; 119 provider_failed_loading = false; 120 121 elog(DEBUG1, "successfully loaded JIT provider in current session"); 122 123 return true; 124 } 125 126 /* 127 * Reset JIT provider's error handling. This'll be called after an error has 128 * been thrown and the main-loop has re-established control. 129 */ 130 void 131 jit_reset_after_error(void) 132 { 133 if (provider_successfully_loaded) 134 provider.reset_after_error(); 135 } 136 137 /* 138 * Release resources required by one JIT context. 139 */ 140 void 141 jit_release_context(JitContext *context) 142 { 143 if (provider_successfully_loaded) 144 provider.release_context(context); 145 146 ResourceOwnerForgetJIT(context->resowner, PointerGetDatum(context)); 147 pfree(context); 148 } 149 150 /* 151 * Ask provider to JIT compile an expression. 152 * 153 * Returns true if successful, false if not. 154 */ 155 bool 156 jit_compile_expr(struct ExprState *state) 157 { 158 /* 159 * We can easily create a one-off context for functions without an 160 * associated PlanState (and thus EState). But because there's no executor 161 * shutdown callback that could deallocate the created function, they'd 162 * live to the end of the transactions, where they'd be cleaned up by the 163 * resowner machinery. That can lead to a noticeable amount of memory 164 * usage, and worse, trigger some quadratic behaviour in gdb. Therefore, 165 * at least for now, don't create a JITed function in those circumstances. 166 */ 167 if (!state->parent) 168 return false; 169 170 /* if no jitting should be performed at all */ 171 if (!(state->parent->state->es_jit_flags & PGJIT_PERFORM)) 172 return false; 173 174 /* or if expressions aren't JITed */ 175 if (!(state->parent->state->es_jit_flags & PGJIT_EXPR)) 176 return false; 177 178 /* this also takes !jit_enabled into account */ 179 if (provider_init()) 180 return provider.compile_expr(state); 181 182 return false; 183 } 184 185 /* Aggregate JIT instrumentation information */ 186 void 187 InstrJitAgg(JitInstrumentation *dst, JitInstrumentation *add) 188 { 189 dst->created_functions += add->created_functions; 190 INSTR_TIME_ADD(dst->generation_counter, add->generation_counter); 191 INSTR_TIME_ADD(dst->inlining_counter, add->inlining_counter); 192 INSTR_TIME_ADD(dst->optimization_counter, add->optimization_counter); 193 INSTR_TIME_ADD(dst->emission_counter, add->emission_counter); 194 } 195 196 static bool 197 file_exists(const char *name) 198 { 199 struct stat st; 200 201 AssertArg(name != NULL); 202 203 if (stat(name, &st) == 0) 204 return S_ISDIR(st.st_mode) ? false : true; 205 else if (!(errno == ENOENT || errno == ENOTDIR)) 206 ereport(ERROR, 207 (errcode_for_file_access(), 208 errmsg("could not access file \"%s\": %m", name))); 209 210 return false; 211 } 212